Networking and Wireless Networking Flashcards

Question

Internet Appliance

Answer 1

An internet appliance is a specialized device that performs a specific network role. The following are some common internet appliances: * Web proxy * Content filter * Malware scanner Internet appliances are typically more expensive than configuring a server to perform the same task. However, internet appliances perform much better and have more features.

Answer 2

VoIP devices provide voice communication over a packet-switched network (an IP network). The most common VoIP device is an IP phone. Instead of using the standard public switched telephone network, IP phones connect to an Ethernet network using an RJ45 connection. Basic VoIP services include Skype or Google Voice. Businesses that use VoIP typically hire a third-party entity (such as Vonage or Jive) to set up the service and configure devices

Answer 3

Networks contain two types of hosts, hosts that consume a service, and hosts that provide a service. Hosts that provide a service are called servers. The following are some of the more common types of servers: * File and Print Server - Provides file sharing and print sharing services. * Application Server - Provides access to a shared network application (a database server that contains customer information). * Directory Server - Handles user authentication. Also stores user credentials, permissions, and settings. * Remote Access Server - Provides remote access to network resources. * Web Server - Serves web pages and web content via HTTP. * DNS Server - Uses the domain name service to map IP addresses to domain names. * DHCP Server - Automatically configures network hosts with an IP address, subnet mask, DNS server, and default gateway

Answer 4

A *bridge* connects two segments within the same subnet. Bridges learn which side a host resides on by copying the MAC address of the source device and placing it into the MAC address table. The port number the frame entered is also recorded in the table and associated with the source MAC address. Another functionality of a bridge is to convert one type of transmission medium into another. A common example of this is a wireless bridge, which converts wired transmissions into wireless transmissions and vice versa

Answer 5

A *router* connects two network segments that have different subnet addresses. * A router has multiple network connections, and each connection is on a different subnet. * Routers use the IP address within a packet to move packets between networks. * Routers maintain a list of known networks and the next router in the path to reach the destination network

Answer 6

A *switch* provides a central connection for multiple media segments on the same subnet. A switch receives a signal on one port and forwards that signal only to the port where the destination device is connected. Switches learn where a device is connected by copying the MAC address of the source device and placing it into the MAC address table. The port number the frame entered is also recorded in the table and associated with the source MAC address. If the switch doesn't know which port a destination device is connected to, it will send the frame in question to all ports. * Switches use the MAC address to send frames to the destination device. * Switches can operate in *full-duplex* mode, where a device uses a different channel for sending and receiving and where the transmission paths are dedicated to only the communicating devices. * You should use a switch instead of a hub in every situation. * Many switches allow you to configure Quality of Service (QoS) settings, which prioritize certain types of network traffic over others. For example, if your network includes Voice over IP (VoIP) telephones, you could increase the priority of VoIP traffic on the switch to increase call quality. * You must configure a switch before you implement it. An unmanaged switch is a low-end switch that you plug it into a power outlet and connect your network devices with UTP cables. While unmanaged switches are convenient and easy to implement, they lack many of the advanced management and security features available. It is preferable to use a managed switch instead. A managed switch is a switch that must be configured before you can use it

Answer 7

A *hub* provides a central connecting point for multiple media segments on the same subnet. When a hub receives a signal, it is sent out to all the ports on the hub. Hubs operate in *half-duplex* mode because the path between devices is shared, meaning that devices can only send when no other devices are sending data. Hubs are a legacy network device and are rarely used because they lack features and perform poorly

Answer 8

A *network adapter* is responsible for creating and receiving transmission signals that are sent along the networking medium. * A network interface card (NIC) uses a cable medium (such as twisted pair or fiber optic cables). * A wireless network adapter transmits radio waves

Answer 9

The networking *medium* provides the path for signals to pass between devices. * Copper cables use electrical signals. * Fiber optic cables use light pulses. * Wireless networks use radio waves or infrared waves. Networking media that use cables are considered bounded, because the transmission signals are contained within the wire. Networks that use wireless communications are considered unbounded

Answer 10

Devices use the MAC address to send frames to other devices on the same subnet. Before two devices can communicate, they must know the MAC address of the receiving device. They do this by using the Address Resolution Protocol (ARP): 1. The sending device sends out a broadcast frame: * The destination MAC address is all Fs (FFFF:FFFF:FFFF). * The sending MAC address is its own MAC address. * The destination IP address is the known IP address of the destination host. * The sending IP address is its own IP address. 2. All hosts on the subnet process the broadcast frame and look at the destination IP address of the packet. 3. If the destination IP address matches its own address, the host responds with a frame that includes its own MAC address as the sending MAC address. 4. The original sender then reads the MAC address from the frame and associates the IP address with the MAC address, saving it in cache. When the sender knows the MAC address of the receiver, it sends data in frames addressed to the destination device

Answer 11

The MAC address is a unique hexadecimal identifier burned into the ROM of every NIC. The MAC address is a 12-digit (48-bit) hexadecimal number. Each number ranges between 0–9 or A–F. The numbers in a MAC address can be divided by dashes (00-B0-D0-06-BC-AC), periods (00B0.D006.BCAC), or colons (00:B0:D0:06:BC:AC). The MAC address is guaranteed unique through design. The first half (first six digits) of the MAC address is assigned to each manufacturer. The manufacturer determines the rest of the address, assigning a unique value which identifies the host address. A manufacturer that uses all the addresses in the original assignment can apply for a new MAC address assignment. Some network cards allow you to change the MAC address through jumpers, switches, or software. However, there is little practical reason for doing so. * The MAC address is a unique hexadecimal identifier burned into the ROM (physically assigned address) of every network interface. * The MAC address is a 48-bit, 12-digit hexadecimal number (each number ranges from 0–9 or A–F). * The address is often written as 00-B0-D0-06-BC-AC or 00B0.D006.BCAC (although dashes, periods, and colons can also be used to divide the MAC address segments). * The MAC address is guaranteed unique through design. * The first half (first 6 digits) of the MAC address is assigned to each manufacturer. * The manufacturer determines the rest of the address, assigning a unique value which identifies the host address. A manufacturer that uses all of the addresses in the original assignment can apply for a new MAC address assignment. * Although some network cards allow you to change the MAC address (or specify one of your own choice), this is rarely done in practice. * When you change the network card, the host will have a new physical device address. * When you move a device to another network, the physical address remains the same (as long as the network card has not been changed).

Answer 12

The network adapter is responsible for converting binary data into a format to be sent on the network medium. A transceiver is responsible for converting digital data into digital signals to be sent on the medium. The type of signal the transceiver sends depends on the type of network. A fiber optic NIC sends light signals, an Ethernet NIC sends electronic signals on a wire, and a wireless NIC sends radio signals. To receive signals, the transceiver converts digital signals from the network to digital data for the PC. A modem converts binary data to analog waves (modulation) on the sending end and then converts the analog waves back to binary data (demodulation) on the receiving end. Most desktop computers have motherboards with built-in network adapters. Practically all mobile devices (i.e., smart phones, tablets, laptops, etc.) have a built-in wireless NIC. Network adapters must match the network medium of the network. Ethernet network adapters that are connected to a switch will operate in full-duplex mode. This allows the adapter to send and receive at the same time

Answer 13

Coaxial cable is primarily used to carry broadband internet signals. Coaxial cable is built with the following components: * The inner conductor carries data signals and is made of solid copper or tin. * The *insulator* surrounds the inner conductor and keeps the signal separated from the mesh conductor. It is made of PVC plastic. * The *braided mesh* conductor is a second physical channel and also functions as a ground. It is made of aluminum or copper-coated tin. * The *sheath* is made of PVC plastic and encases the cable, protecting it from external elements.

Answer 14

Coaxial cable is primarily used to carry broadband internet signals. Coaxial cable is built with the following components: * The inner conductor carries data signals and is made of solid copper or tin. * The *insulator* surrounds the inner conductor and keeps the signal separated from the mesh conductor. It is made of PVC plastic. * The *braided mesh* conductor is a second physical channel and also functions as a ground. It is made of aluminum or copper-coated tin. * The *sheath* is made of PVC plastic and encases the cable, protecting it from external elements.

Answer 15

Because RG-6 is able to carry a higher-quality signal with much lower signal loss than RG-59, RG-6 cabling should always be used for any coaxial cable implementation **Type** **Uses** **Resistance Rating** RG-59 CCTV video systems; short cable lengths (less than 3 meters) are sometimes used for cable TV 75 ohms RG-6 Cable TV, satellite TV, and broadband cable internet 75 ohms

Answer 16

* Molded onto the cable * Used in legacy 10Base2 Ethernet networks * Used in specialized industries * Used to connect composite video displays on commercial video devices.

Answer 17

* Four pairs of copper wires carry the data signals (one wire in the pair carries a positive signal, the other carries a negative signal). Wires are twisted into pairs to reduce the effects of electromagnetic interference and crosstalk. * PVC plastic insulation surrounds each copper wire. * An outer plastic sheath bundles the wires together and protects them. * Unshielded twisted pair (UTP) has only an outer plastic sheath. UTP cables are easier to work with and are less expensive than shielded cables. * Shielded twisted pair (STP) has a grounded outer copper shield around the entire wire bundle or around each wire pair. STP provides additional EMI protection, but costs considerably more than UTP.

Answer 18

**Advantages** **Disadvantages** * Inexpensive compared to other media types * Easy to install and manage * Very common (media and tools are easy to obtain) * The most common (and most supported) network medium * Very susceptible to EMI * Cables are easily damaged * Vulnerable to eavesdropping

Answer 19

**Category** **Connector** **Speed** **Frequency** **Description** Phone cable RJ11 10 Mbps N/A Used to connect a modem to a phone jack in a wall outlet to establish a dial-up internet connection Has two pairs of cable (a total of 4 wires). Cat 5 RJ45 100 Mbps 100 MHz Supports up to 100 Mbps Ethernet. Cat 5e RJ45 1000 Mbps 100 MHz Similar to Cat 5 but provides better EMI protection. Supports gigabit Ethernet (gigabit connections require the use of all four twisted pairs) Cat 6 RJ45 10 Gbps 250 MHz 10 Gbps speeds are limited to cable lengths less than 55 meters. Cat 6a RJ45 10 Gbps 500 MHz 10 Gbps speeds are limited to cable lengths less than 100 meters. Provides additional shielding and tighter cable twists than standard Cat 6, which reduces (alien) crosstalk and makes it less susceptible to EMI. Cat 7 RJ45 10 Gbps 600 MHz Has the strictest specifications for crosstalk and noise.

Answer 20

**Connector** **Description** RJ11 * Has 4 or 6 connectors * The RJ-11 wiring standard supports up to 2 pairs of wires (one phone and one power) * Uses a locking tab to keep a connector secure in an outlet * Used primarily for telephone wiring * The RJ-14 and RJ-25 wiring standard support additional phone lines using the same jack RJ45 * Has 8 connectors * Supports up to 4 pairs of wires * Uses a locking tab to keep a connector secure in an outlet * Used for Ethernet networks

Answer 21

* Use a crimping tool designed for RJ45 connectors to attach connectors to UTP cable. Most crimping tools include an integrated wire stripper that you can use to remove the outer sheath from the cable so you can access the individual wires. * Cat 5/5e/6/6a cables come with wires that have solid cores or stranded cores. Use solid core cables for longer runs inside walls or the ceiling; use stranded wires for drop cables where flexibility and frequent movement occurs. * There are different connectors rated for solid or stranded core wires; be sure to use the correct connector type. * To reduce crosstalk, keep the pairs twisted as much as possible right up to the connector. * Making Cat 6 compliant cables is difficult; if you do not add the connectors exactly right, the cable will be capable of only 100 Mbps speeds. In most cases, it would be easier to buy cables of the correct length than to try and make your own. * Be sure you use the appropriate punch-down tool when connecting UTP cabling to a punch-down block. To use a punch-down tool, position the UTP wire into a slotted post in the punch-down block. Then press down on the top of the wire over the post with the punch-down tool

Answer 22

* Cat 5 Ethernet (100BASE-T) and below (Tx is a pin used for transmitting and Rx is a pin used for receiving): * Pin 1: Tx+ * Pin 2: Tx- * Pin 3: Rx+ * Pin 4: Unused * Pin 5: Unused * Pin 6: Rx- * Pin 7: Unused * Pin 8: Unused * Cat 5e (1000BASE-T) and above (Bi indicates the pin is used for both transmitting and receiving): * Pin 1: Bi+ D0 * Pin 2: Bi- D0 * Pin 3: Bi+ D1 * Pin 4: Bi+ D2 * Pin 5: Bi- D2 * Pin 6: Bi- D1 * Pin 7: Bi+ D3 * Pin 8: Bi- D3

Answer 23

Computers connect to the network through a hub or switch with a patch cable. Patch cables use the same wire configuration on each connector end. The following are the two most commonly used wiring configurations: * T568A Wires are arranged from pins 1 to 8 in each connector in the following order: GW, G, OW, B, BW, O, BrW, Br. * T568B Wires are arranged from pins 1 to 8 in each connector in the following order: OW, O, GW, B, BW, G, BrW, Br. It doesn't matter which standard is used as long as all cables use the same standard. This helps prevent confusion during troubleshooting

Answer 24

Computers can connect directly to one another using a crossover cable. The easiest way to create a crossover cable is to arrange the wires in the first connector using the T568A standard and arrange the wires in the second connector using the T568B standard.

Answer 25

* The central core carries the signal. It is made of plastic or glass. * The cladding maintains the signal in the center of the core as the cable bends. * The protective layer provides a stiff structure to prevent the cladding and central core from breaking. * The plastic sheath encases everything and protects the cable.

Answer 26

**Advantages** **Disadvantages** * Completely immune to EMI * Highly resistant to eavesdropping * Fastest available transmission rates * Greater cable distances without a repeater * Very expensive * Difficult to work with * Special training required to attach connectors to cables

Answer 27

* Transfers data through the core using a single light ray (the ray is also called a mode) * Has a core diameter of around 10 microns * Supports a large amount of data * Allows cable lengths to extend a great distance

Answer 28

* Transfers data through the core using multiple light rays * Has a core diameter of around 50 to 100 microns * Limits the distance of cable lengths

Answer 29

ST Connector * Used with single mode and multi-mode cabling * Keyed, bayonet-type connector * Also called a push in and twist connector * Each wire has a separate connector * Nickel plated with a ceramic ferrule to ensure proper core alignment and prevent light ray deflection * As part of the assembly process, it is necessary to polish the exposed fiber tip to ensure that light is passed on from one cable to the next with no dispersion

Answer 30

SC Connector * Used with single mode and multi-mode cabling * Push on, pull off connector type that uses a locking tab to maintain connection * Each wire has a separate connector * Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection * As part of the assembly process, it is necessary to polish the exposed fiber tip

Answer 31

LC Connector * Used with single mode and multi-mode cabling * Composed of a plastic connector with a locking tab, similar to an RJ45 connector * A single connector with two ends keeps the two cables in place * Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection * Half the size of other fiber optic connectors

Answer 32

MT-RJ Connector * Used with single mode and multi-mode cabling * Composed of a plastic connector with a locking tab * Uses metal guide pins to ensure it is properly aligned * A single connector with one end holds both cables * Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection

Answer 33

**Component** **Description** Network Interface Card A network interface card (NIC) creates the signals that are sent along the networking medium. * A transceiver built into the network adapter formats the binary data for transmission on the network medium. * Ethernet devices are identified using the MAC address, which is burned into the network interface card. Networking Media Ethernet supports the following cable types: * Unshielded twisted-pair cables (UTP) with RJ45 connectors. This is the most common transmission medium used for Ethernet. * Fiber optic cables, which are used in high-speed applications (such as servers or streaming media). * Coaxial cable with F-type connectors for cable internet services. Coaxial cable is also used for older Ethernet implementations ( which are often called *thinnet* or *thicknet* networks). Connectivity Devices Ethernet uses the following connectivity devices: * A hub provides a central connection for multiple media segments on the same subnet. When a hub receives a signal, it is repeated out to all other ports. Hubs operate in half-duplex mode, meaning devices can either send or receive data at any given time. Hubs are rarely used in networking environments. You should avoid them if possible. * A switch provides a central connection for multiple media segments on the same subnet. When a switch receives a signal, it forwards that signal only to the port where the destination device is connected. * Switches use the MAC address to send frames to the destination device. * Switches operate in full-duplex mode, meaning devices can send and receive data at the same time because transmission paths are dedicated to only the communicating devices. * When possible, use switches instead of hubs. * A router connects two network segments that have different subnet addresses. * A router has multiple network connections. Each connection is on a different subnet. * Routers use the IP address within a packet to move packets between networks. * A bridge connects two segments within the same subnet that use different media types. For example, you can use a bridge to connect wireless clients to wired clients on the same network. * A patch panel is a device that is commonly used to connect individual stranded wires into female RJ45 connectors. For example, you might connect four pairs of wires from a punchdown block to a port on the patch panel. On the patch panel, you then connect drop cables (cables with RJ45 connectors) to the patch panel on one end and a computer on the other end. * An Ethernet over power device allows network communications to be transmitted over existing AC power lines. An Ethernet over power device is plugged in to one AC power outlet, and a second Ethernet over power device is connected to the same AC circuit. These devices multiplex the AC copper power lines to transmit digital network signals at a frequency higher than the AC electrical power already on the circuit. Standards Ethernet standards identify the transmission speed and the cable type. Data transfer rates range from 10 Mbps (very old Ethernet networks) up to 10 Gbps. Between 100 and 1000 Mbps are the most common speeds for most networks. Distance Ethernet standards define the maximum distance for cable lengths between two devices. * The maximum cable length for UTP Ethernet "T" implementations is 100 meters for all standards. * The length for fiber optic cables varies depending on the cable type and specification, but typically ranges from 100 meters to 40 kilometers. Power over Ethernet Power over Ethernet (PoE) technology is used to distribute electrical power along with network data on twisted-pair Ethernet cabling (CAT 5 or higher). Power is usually supplied by a PoE-enabled Ethernet switch. PoE is commonly used to power network devices that are located where physical access to a power outlet may not be available. For example, a PoE-enabled surveillance camera mounted on a tall pole can be powered via its Ethernet cabling. You can use a Power over Ethernet (PoE) injector to add PoE capability to regular non-PoE network links. PoE injectors can be used to upgrade existing LAN installations to PoE and provide a solution where fewer PoE ports are required. To upgrade a network connection to PoE, patch it through the PoE injector. Power injection is controlled and automatic.

Answer 34

**Category** **Standard** **Bandwidth** **Cable Type** **Maximum Segment Length** Ethernet 10BaseT ``` 10 Mbps (half-duplex) 20 Mbps (full-duplex) ``` Twisted pair (Cat 4 or 5) 100 meters 10BaseFL 10 Mbps (multimode cable) Fiber optic 1,000 to 2,000 meters Fast Ethernet 100BaseTX ``` 100 Mbps (half-duplex) 200 Mbps (full-duplex) ``` Twisted pair (Cat5 or higher) Uses 2 pairs of wires 100 meters 100BaseFX 100 Mbps (multimode cable) Fiber optic 412 meters Gigabit Ethernet 1000BaseT 1,000 Mbps (half-duplex) 2,000 Mbps (full-duplex) Twisted pair (Cat5 or higher) 100 meters 1000BaseCX (short copper) Special copper (150 ohm) 25 meters, used within wiring closets 1000BaseSX (short) Fiber optic 220 to 550 meters depending on cable quality 1000BaseLX (long) ``` 550 meters (multimode) 10 kilometers (single-mode) ``` 10 Gigabit Ethernet 10GBaseT 10 Gbps (full-duplex only) Twisted pair (Cat6, or 7) 100 meters 10GBaseSR/10GBaseSW Multimode fiber optic 300 meters 10GBaseLR/10GBaseLW Single-mode fiber optic 10 kilometers 10GBaseER/10GBaseEW Single-mode fiber optic 40 kilometers

Answer 35

* Is a 32-bit binary number represented as four octets (four 8-bit numbers). Each octet is separated by a period. * Can be represented in one of two ways: * Decimal (e.g., 131.107.2.200). In decimal notation, each octet must be between 0 and 255. * Binary (e.g., 10000011.01101011.00000010.11001000). In binary notation, each octet is an 8-digit number. * Includes both the network address and the host address. * Uses a *subnet mask* to differentiate the network and host addresses. * The IP address identifies both the logical host and the logical network addresses. * Each host on the entire network must have a unique IP address. * Two devices on the same subnet must have IP addresses with the same network portion of the address. * Two devices on the same subnet must have unique host portions of the IP address. * Do not use the first or the last host address on a subnet address range.

Answer 36

Another way to differentiate the network and host addresses is by using CIDR block notation. With CIDR, the network address is specified by appending a slash (/) followed by the number of bits that are part of the network address. For example, the subnet mask 255.255.0.0 is written as /16 in CIDR notation (the network address consists of the first two octets, or the first 16 bits). IP addresses use default classes that includes a default subnet mask value. The *class* defines the default network address portion of the IP address. **Address Range** **Class** **Default Subnet Mask** **CIDR** 1.0.0.0 to 126.255.255.255 A 255.0.0.0 /8 128.0.0.0 to 191.255.255.255 B 255.255.0.0 /16 192.0.0.0 to 223.255.255.255 C 255.255.255.0 /24 224.0.0.0 to 239.255.255.255 D N/A N/A 240.0.0.0 to 255.255.255.255 E N/A N/A The IP address 192.168.6.11 is an example of a Class C address, which uses a default mask of 255.255.255.0. With this address, the network address is 192.168.6.0, and the host address is 11. Know that the address range from 0.0.0.0 to 0.255.255.255 is reserved for broadcast messages to the current network. The address range from 127.0.0.0 to 127.255.255.255 is reserved for loopback addresses to the local host. Instead of using the default subnet mask, it is possible to use custom subnet masks to define different network addresses. This process is called *subnetting* and typically uses CIDR notation

Answer 37

A protocol is a rule that identifies some aspect of how computers communicate on a network. For two computers to communicate, they must be using the same protocols. Protocols are grouped into protocol suites, or sets of related protocols, that are meant to be used together

Answer 38

TCP/IP is the protocol suite used on the internet and on most networks. Nearly all computers today use TCP/IP for communication. The Internet Protocol (IP) is a key component of the TCP/IP protocol suite. The IP protocol is responsible for determining how to deliver data from the sending host to the destination host. However, it does not provide a mechanism for segmenting and sequencing packets in a communication. To accomplish this, IP is used in conjunction with another transport protocol: * Transmission Control Protocol (TCP) - TCP is a connection-oriented protocol. To ensure reliable delivery of data, TCP requires the recipient of a network transmission to send an acknowledgement of each and every IP packet it receives to the sender. Packets that don't make it are retransmitted. This ensures that the data is delivered reliably. User Datagram Protocol (UDP) - UDP is a connectionless protocol. Unlike TCP, UDP does not require acknowledgements. One of the key drawbacks of using TCP is the fact that its reliability introduces latency. For small data transmissions, such as sending an email, moderate latency is not a problem. However, for large data transmissions, such as video or audio streaming, the latency associated with TCP is unacceptable. By using UDP instead, the latency of the transmission is significantly reduced, with the assumption that an occasional lost packet won't be detrimental.

Answer 39

NetBIOS is the term used to describe the combination of two protocols: NetBEUI and NetBIOS. NetBIOS was used in early Windows networks. Because NetBIOS is a non-routable protocol, it was often combined with IP to enable internetwork communications. NetBIOS over TCP/IP, or NetBT, is used to allow older computers and applications that rely on NetBIOS to communicate on a TCP/IP network.

Answer 40

Default port 80 HTTP is used by web browsers and web servers to exchange files (such as web pages) through the World Wide Web and intranets. HTTP can be described as an information requesting and responding protocol. It is typically used to request and send web documents, but is also used as the protocol for communication between agents using different IP protocols.

Answer 41

Default port 443 HTTPS is a secure form of HTTP that uses SSL as a sublayer for security. SSL secures messages being transmitted on the internet. It uses RSA for authentication and encryption. Web browsers use SSL (Secure Sockets Layer) to ensure safe web transactions. URLs that begin with https:// trigger your web browser to use SSL.

Answer 42

Default port: 20, 21 FTP provides a generic method of transferring files. It can include file security through usernames and passwords, and it allows file transfer between dissimilar computer systems. FTP can transfer both binary and text files, including HTML, to another host. FTP URLs are preceded by ftp:// followed by the DNS name of the FTP server. To log into an FTP server, use: ftp://username@servername.

Answer 43

Default port: 25 SMTP is used to route electronic mail through the internetwork. Email applications provide the interface to communicate with SMTP or mail servers.

Answer 44

Default port: 143 IMAP is an email retrieval protocol designed to enable users to access their email from various locations without the need to transfer messages or files back and forth between computers. Messages remain on the remote mail server and are not automatically downloaded to a client system.

Answer 45

Default port: 110 POP3 is part of the IP protocol suite and used to retrieve email from a remote server to a local client over an IP connection. With POP3, email messages are downloaded to the client.

Answer 46

Default port: 23 Telnet allows an attached computer to act as a dumb terminal, with data processing taking place on the IP host computer. It is still widely used to provide connectivity between dissimilar systems. Telnet can also be used to test a service by the use of HTTP commands. You should avoid using Telnet as it transmits all data (e.g., usernames and passwords) clear text

Answer 47

Default port: 22 SSH allows for secure interactive control of remote systems. SSH is a much more secure alternative to Telnet.

Answer 48

Default Port: 22 SFTP addresses one of the key weaknesses of FTP; namely, FTP doesn't use encryption. All data, including usernames and passwords, is sent clear text. SFTP provides the same functionality as FTP, but secures the data transmissions using the SSH protocol

Answer 49

Default port: 53 DNS is a system that is distributed throughout the internetwork to provide address/name resolution. For example, the name www.mydomain.com would be identified with a specific IP address

Answer 50

Default Port: 3389 RDP allows you to view and use the graphical desktop of a remote computer system as if you were sitting in front of it

Answer 51

Default Port: 67, 68 DHCP is used to dynamically assign IP addressing information to network hosts when they come online. The client system, when it connects to the network, broadcasts a DHCPDISCOVER message on the network, looking for a DHCP server. The DHCP server responds with a DHCPOFFER message containing proposed IP addressing configuration information. The client then responds with a DHCPREQUEST message to the DHCP server indicating it wants to use the proposed configuration. The DHCP server makes the assignment with a DHCPACK message.

Answer 52

Default Port: 389, 636 LDAP is a protocol used to access information about network resources stored by a directory service, such as Active Directory or eDirectory. LDAP uses port 389 for clear text transmissions and port 636 for secure transmissions.

Answer 53

Default Port: 161, 162 SNMP is used to monitor and manage network devices. SNMP agents can be installed on network devices such as PCs, switches, and routers. These agents send data to an SNMP manager application running on an administrative workstation, which aggregates the information and displays an overview of the current network status. Thresholds can be configured which trigger alerts if exceeded.

Answer 54

Default Port: 445 SMB enables the sharing of folders and printers on the network. Using SMB, remote users can access files in a shared folder on a server or workstation. Likewise, a remote user can send print jobs to a shared printer. SMB is also known as *Common Internet File System* (CIFS). SMB running directly over TCP uses port 445. SMB running on "NetBIOS over TCP/IP" uses UDP ports 137 & 138 and TCP ports 137 & 139.

Answer 55

Default Port: 427 SLP is a protocol that is able to organize and locate various network devices and services, such as printers, shared disk drives, directories, etc.

Answer 56

Default Port: 548 AFP is the protocol used by systems running Mac OS X or newer to support file sharing on the network. AFP replaced AppleTalk and has gone through several revisions.

Answer 57

The subnet mask identifies which portion of the IP address is the network address and which portion is the host address. Two devices on the same subnet must be configured with the same subnet mask.

Answer 58

The default gateway identifies the router to which communications for remote networks are sent. The default gateway address is the IP address of the router interface on the same subnet as the local host. Without a default gateway set, most clients will be unable to communicate with hosts outside of the local subnet.

Answer 59

The DNS server address identifies the DNS server that is used to resolve host names to IP addresses.

Answer 60

The DNS server address identifies the DNS server that is used to resolve host names to IP addresses

Answer 61

The hostname identifies the logical name of the local system

Answer 62

With static addressing, you manually assign all configuration values. Static addressing is prone to error and should be used only under the following conditions: * The network has a small number of hosts. * The network will not change or grow. * You have some hosts that must have the same address each time.

Answer 63

On a network configured with DHCP, IP hosts contact a DHCP server for IP addressing and other configuration information. This ensures error-free host configuration. With DHCP: * The host uses broadcast messages to locate a DHCP server when it boots. * The DHCP server assigns IP address and mask values to the host (called an address *lease*). * The DHCP server ensures that no two hosts are assigned the same IP address. * You can configure the DHCP server to deliver default gateway, DNS server, and other configuration information to hosts. DHCP requires a special DHCP server, which is built-in to most SOHO routers

Answer 64

If a Windows client is configured to receive an IP address from a DHCP server, but cannot contact a DHCP server, it will automatically assign itself an IP address within the following range: 169.254.0.1 to 169.254.255.254 with the subnet mask 255.255.0.0 With APIPA: * The host is configured to obtain IP information from a DHCP server (this is the default configuration). * If a DHCP server cannot be contacted, the host uses APIPA to assign itself an IP address. * The host configures only the IP address and mask. It does not assign itself the default gateway and DNS server addresses. For this reason, APIPA can be used only on a single subnet. You can use APIPA instead of a DHCP server, but it should be used only on a small network that does not need default gateway or DNS server settings configured. APIPA is the term used by Microsoft Windows. On other systems (e.g., Linux), this functionality is known as link-local addressing.

Answer 65

With an alternate IP configuration, the system attempts to use DHCP for TCP/IP configuration information. If a DHCP server cannot be contacted, the static configuration values are used. When you configure an alternate IP address, APIPA is no longer used. Use an alternate configuration: * If you have a computer (e.g., a laptop) that connects to two networks (i.e., one with a DHCP server and another without a DHCP server). * If you want to provide values to properly configure the computer in case the DHCP server is unavailable.

Answer 66

* By default, all Windows computers try to use DHCP for TCP/IP configuration information. * If your computer has used APIPA because the DHCP server is unavailable, it will have an IP address in the 169.254.*x*.*x* range. The workstation will be able to communicate with other hosts that have addresses in this range, but will not be able to communicate with hosts on other networks. * When you configure a static IP address, you disable DHCP and APIPA. * If you use a DHCP server for IP address configuration, you can still manually configure DNS server addresses. * By default, a Windows workstation will use the hosts file to resolve hostnames into IP addresses first. If a match can't be found for the hostname to be resolved in the hosts file, the workstation will contact the DNS server it has been configured to use.

Answer 67

IP version 6 (IPv6) was developed to address the fact that IPv4 addresses have been exhausted. The IPv6 address is a 128-bit binary number. The following list describes the features of an IPv6 address: * The address is made up of 32 hexadecimal numbers organized into 8 quartets (for example, 35BC:FA77:4898:DAFC:200C:FBBC:A007:8973). * The quartets are separated by colons. * Each quartet is represented as a hexadecimal number between 0 and FFFF. Each quartet represents 16 bits of data (FFFF = 1111 1111 1111 1111). * Leading zeros can be omitted in each section. For example, the quartet 0284 could also be represented by 284. * Addresses with consecutive zeros can be expressed more concisely by substituting a two colons for the group of zeros. For example: * FEC0:0:0:0:78CD:1283:F398:23AB * FEC0::78CD:1283:F398:23AB (concise form) * If an address has more than one consecutive location where one or more quartets are all zeros, only one location can be abbreviated. For example, FEC2:0:0:0:78CA:0:0:23AB could be abbreviated as: FEC2::78CA:0:0:23AB or FEC2:0:0:0:78CA::23AB, but not FEC2::78CA::23AB

Answer 68

**Component** **Description** Prefix The first 64 bits are known as the prefix. * The 64-bit prefix can be divided into various parts and each part has a specific meaning. Parts in the prefix can identify the geographic region, the ISP, the network, and the subnet. * The prefix length identifies the number of bits in the relevant portion of the prefix. To indicate the prefix length, add a slash (/) followed by the prefix length number. Full quartets with trailing 0s in the prefix address can be omitted (for example, 2001:0DB8:4898:DAFC::**/**64). * Because addresses are allocated based on physical location, the prefix generally identifies the location of the host. The 64-bit prefix is often referred to as the global routing prefix. Interface ID The last 64 bits are the interface ID. This is the unique address assigned to an interface. * Addresses are assigned to interfaces (network connections), not to the host. Technically, the interface ID is not a host address. * In most cases, individual interface IDs are not assigned by ISPs, but are rather generated automatically or managed by site administrators. * Interface IDs must be unique within a subnet, but can be the same if the interface is on different subnets. * On Ethernet networks, the interface ID can be automatically derived from the MAC address. Using the automatic host ID simplifies administration.

Answer 69

A dial-up connection uses a modem connected to the phone line to connect to the internet. * Dial-up connections use the public switched telephone network (PSTN). Phone lines are sometimes referred to as POTS (plain old telephone service). * Multiple standards define how to send digital data over the analog phone lines at various speeds and compression ratios. * Dial-up connections are available anywhere a telephone line exists. * Data transfer rates include 28.8 Kbps, 33.3 Kbps, and 56 Kbps. * Dial-up connections cannot be used for both voice (phone calls) and data at the same time.

Answer 70

DSL provides broadband digital data transmission over existing telephone lines. * DSL divides the telephone line into multiple channels. One channel is used for analog voice, while the remaining channels are used for digital data. * Filters are used to separate the analog voice data from digital data. * Several DSL standards exist, including ADSL, SDSL, and HDSL (collectively referred to as xDSL). * Depending on the type of DSL used, you can use the same line for simultaneous voice and data. * DSL is not available in all areas; the service location must be within a fixed distance of telephone switching equipment.

Answer 71

ISDN is a digital service, running over a switched network. * There are two versions of ISDN: * ISDN BRI divides the regular copper telephone line into three channels: * 2 64-Kbps bearer (B) channels can transfer data up to 128 Kbps (data compression increases the data transfer rate). Only one B channel is used during phone use reducing maximum speed to 64 Kbps. * 1 16-Kbps delta (D) channel for connection control. * ISDN PRI requires different cables to be installed rather than the regular phone lines. The cable is divided into 24 channels: * 23 B channels (each at 64 Kbps) for data transmission. * 1 D channel (at 64 Kbps) for connection control. * ISDN is not available in all areas; subscribers are required to be within a certain proximity of telephone company equipment. * ISDN is more common in Europe than in the United States.

Answer 72

Cable networking uses a cable TV connection to create a wide area connection to the internet. * A cable modem (router) connects the computer to the cable network for sending networking signals. * The same cable line is used to carry networking and cable TV signals, although in some cases a separate line is installed for internet access. * Cable networking requires the installation of a cable TV line to your location if one does not exist.

Answer 73

Cellular networking uses the cellular phone infrastructure for internet access. * Mobile phones with digital data plans use cellular signals to connect to the internet. * Devices can connect to a cellular internet connection in a variety of ways: * Many smart phones use a technique known as *tethering* to provide cellular internet to another device. Tethering typically requires the smart phone to be connected via a USB cable. * A mobile hotspot is a cellular device that provides internet access by creating a small Wi-Fi network to which multiple devices can connect. Most smart phones have built-in mobile hotspot functionality. * Some mobile devices (e.g., notebook computers and tablets) have integrated cellular antennas. * USB cellular adapters can be connected to most mobile devices to provide cellular access. * Cellular networking is a truly mobile solution. You can often be moving and still have internet access without manually having to reconnect. * Internet access is limited to areas with cell phone coverage. Coverage will be dictated by the service provider's network. Cellular networks used for voice and data include the following types: * 2G (second generation) networks were the first to offer digital data services. 2G data speeds are slow (14.4 Kbps) and were used mainly for text messaging and not internet connectivity. * 2.5G was an evolution that supported speeds up to 144 Kbps. * EDGE (also called 2.75G) networks are an intermediary between 2G and 3G networks. EDGE is the first cellular technology to be truly internet compatible, with speeds between 400 and 1,000 Kbps. * 3G (third generation) offers simultaneous voice and data. The minimum speed for stationary users is quoted at 2 Mbps or higher. * 4G (fourth generation) offers minimum speeds of around 38 Mbps, with up to 100 Mbps possible

Answer 74

Satellite networking uses radio signals sent and received from a satellite. Satellite networking is divided into two categories, Geostationary Satellites (GEOs) and Low Earth Orbit Satellites (LEOs). Geostationary Satellite (GEO): * Uses a transmitter with an antenna (dish) directed skywards to a satellite * Requires line-of-sight to the satellite (dish placement is crucial) * Is affected by mild atmospheric and weather conditions (fog, rain, or snow can disrupt service) * May have a long delay time (latency) between requests and downloads * Can be a portable solution for cars or trucks with an attached satellite dish * Provides nearly 100% global coverage Low Earth Orbit Satellite (LEO): * Closer to the Earth than GEOs * Orbits at a distance of about 1200 miles above the Earth * Simpler and cheaper to make than GEOs * Fast, accurate communication and service * Coverage area is limited; needs more satellites to cover a bigger area Some satellite internet access solutions are limited to download only. Another solution, such as dial-up, is required to provide upload capabilities

Answer 75

Line of site internet access (also called fixed wireless broadband) is similar to satellite internet; however, instead of antennas being directed to a satellite in orbit, they are pointed at a large antenna on land. The antennas use radio signals--typically microwaves--to transmit and receive data. Line of site internet: * Requires a direct line of site between two fixed antennas. A single, large antenna provides connections for all subscribers in an area * Provides internet access without needing to run cables or lines to each subscriber's premise * Can provide internet to remote areas by installing a single antenna * Ss affected by weather conditions, similar to satellite networking * Offers speeds of up to 1520 Mbps

Answer 76

Voice over IP (VoIP) sends voice phone calls using the TCP/IP protocol over digital data lines. * With VoIP, phone calls are made through your internet connection, not through a phone line. * When you make a phone call, the call is converted into digital data and sent through the internet. * VoIP is provided by many ISPs to replace existing analog telephone lines (even using the same phone number). * Desktop computers can be used to make VoIP calls by using VoIP software and the computer's microphone and speakers. The most common example of this is the VoIP application Skype

Answer 77

**ipconfig** displays IP configuration information for network adapters. Use the **ipconfig** command as follows: * Use **ipconfig** to view IP address, subnet mask, and default gateway configuration. * Use **ipconfig /all** to view detailed configuration information, including the MAC address and the DHCP server used for configuration. * Use **ipconfig /release** to release the IP configuration information obtained from the DHCP server. * Use **ipconfig /renew** to request new IP configuration information from the DHCP server. * Use **ipconfig /displaydns** and **ipconfig /flushdns** to view and manage the local DNS cache. The first command displays the contents of the local DNS cache that Windows maintains and updates every 24 hours. The second option flushes (or removes) all the entries in the current DNS cache. If the IP address of a network server is changed, your local cache will contain the old IP address until the cache is updated or the **flushdns** option is used.

Answer 78

**ifconfig** is used on Linux and macOS systems and displays the installed network interfaces and the current configuration settings for each interface, including the MAC address, IP address, broadcast address, and subnet address. Use the **ifconfig** command as follows: * Use **ifconfig *[interface\_name]* down** to disable the specified network interface. * Use **ifconfig *[interface\_name]* up** to enable the specified network interface. Use the following utilities to display additional networking information not provided by ifconfig: * The **hostname** command displays the system's hostname. * The **route** command displays the default gateway configuration settings. On Linux systems, the **iwconfig** command is used to display information about wireless network interfaces

Answer 79

**ping** sends an ICMP echo request/reply packet to a remote host. A response from the remote host indicates that both hosts are correctly configured and a connection exists between them. You can ping a host by IP address or use the DNS name. When the DNS name is used, the computer must look up the corresponding IP address before performing the ping test. * **-a** looks up the hostname from a given IP address. * **-t** performs a continuous ping test (press **Ctrl** + **C** to stop sending the ping tests). **-l *[size]*** specifies the packet payload size (in bytes) to use in the test. This can help determine whether packets above a certain size are being lost

Answer 80

**tracert** is similar to the **ping** utility because it tests connectivity between devices; however, **tracert** also shows the path between the two devices. Responses from each hop on the route are measured three times to accurately report how long the packet takes to reach the specific host and then return. * On a Windows system, use the **tracert** command. * On Linux and macOS systems, use the **traceroute** command

Answer 81

nslookup resolves (looks up) the IP address of the specified hostname. It also displays additional name resolution information, such as the DNS server used for the lookup request

Answer 82

**netstat** displays the following IP-related statistics: * Current connections * Incoming and outgoing connections * Active sessions, ports, and sockets * The local routing table

Answer 83

**nbtstat** is used to diagnose issues regarding NetBIOS over TCP/IP. You can use the following options with **nbtstat**: * **-c** displays the NetBIOS cache of remote machine names and their IP addresses. * **-n** displays NetBIOS names that have been registered on the local system. * **-r** displays names resolved by broadcast and via WINS. * **-R** clears and then reloads the remote cache name table. * **-S** displays current NETBIOS sessions with the destination IP addresses. * **-s** displays current NETBIOS sessions by NETBIOS names

Answer 84

The Telnet utility is used for remote server management. * The Telnet protocol must be running and configured on the remote server in order for a Telnet session to be established. * By default, Telnet does not encrypt transmissions (they are sent as clear text). * Telnet is mostly used by specialized industrial and scientific devices. In addition to sending transmissions in clear text, there are several well-known vulnerabilities in the Telnet protocol. Because of this, Telnet should not be used when sending sensitive information

Answer 85

Like Telnet, the SSH utility is used for remote server management; however, SSH encrypts all communications and is much more secure. * SSH can be used to remotely log onto a server and complete configuration tasks. * In order to establish an SSH session, the server must have the SSH process running and configured to allow remote connections. * Use the following syntax to establishing an SSH connection: ** ssh *[username]*@*[server\_address]***

Answer 86

**Step** **Description** Verify the network adapter Verify that your computer has detected and properly configured the network adapter card. * To view a list of available network connections, do one of the following: * In the notification area, right-click the **Network** icon and select **Open Network & Internet settings**. Select **Change adapter options**. * In Windows 8 and Windows 10, right-click **Start** and select **Network Connections**. * If the network interface card is detected and configured, you should see an Ethernet or Wi-Fi icon in the Network Connections window. Make sure that the connection is enabled. * If there is no icon, check Device Manager to make sure that the device is detected, has the appropriate drivers, and is enabled. If there is no network device, then the hardware could not be detected. Verify physical connectivity If you have a network connection in Windows, verify that the adapter can establish a physical connection to the network. * For wired connections: * The notification area includes a Network icon that indicates the physical status of the connection. If the cable is unplugged or the NIC cannot find a connected device, the Network icon will have an X on it. * Check the status lights on the back of the NIC to verify the physical status. There should be a link light that is green. An unlit link light or one that is another color (like red or yellow) indicates a physical connectivity problem. * For wireless connections: * The notification area includes a Wireless Network icon that indicates the connection status. If the computer is not connected to any wireless network, the icon will have an X on it. * Make sure the wireless NIC is installed properly and, if applicable, has any necessary antennae installed. If you suspect a problem with the physical connection, try the following: * For wired connections: * Use a different network cable that you know works. You can use a cable tester or cable certifier to test the network cabling behind the wall between the wall jack and the punch-down panel. You can also use a tone generator (sometimes called a toner) and probe to trace the location of cables through the wall and ceiling. * Connect the cable to a different hub or switch port and check the status lights on the port. * Try installing a different network adapter, such as an external adapter that connects through a USB port. * For wireless connections: * Verify that the SSID settings are correct. If the SSID is hidden, make sure the manually entered SSID has been entered correctly. * Make sure both the authentication type and passphrase are correct. * If MAC address filtering is being used, ensure the device has been properly configured on the access point. * If the SSID is hidden, make sure the manually entered SSID has been entered correctly. * Use a wireless analyzer, which can be installed on a smart phone or tablet, to do the following: * Locate wireless networks. * Identify crowded channels or sources of interference. * Find locations with poor wireless coverage. * Detect rogue access points. Verify the IP configuration If the network adapter has a physical connection, verify the IP configuration for the connection. * Use **ipconfig** to view the IP address, subnet mask, and default gateway configured for the system. * Use **ipconfig /all** to view additional information including the MAC address of the network adapter and the DNS server addresses. * Verify that all configuration values are correct. * If the computer is using DHCP and if you see an IP address beginning with 169.254.x.x and a mask of 255.255.0.0, the computer was not able to contact the DHCP server and used the APIPA feature to configure the address automatically. In this case, verify that the DHCP server is connected to the network and properly configured. Verify network communication If the computer has a valid network connection and IP configuration values are correctly set, you can use the **ping** command to test connectivity with other network hosts. Ping sends out a request that is answered by the destination device. * If the ping test succeeds, the destination device is working. If you are still having problems, check issues with logon, resource sharing, permissions, or services. * If the ping test fails only to that device, then the device might not be properly configured. * If a ping test fails to any network device, check routers and other devices. * You can use the host name with the **ping** command. If you can ping the device by the IP address but not the host name, then the problem is likely with the DNS configuration. Be aware that many devices are now configured not to respond to ping requests. A failed ping test might not give you reliable information about the status of network devices.

Networking and Wireless Networking Flashcards

(110 cards)