1
Q
IP addresses are __-bit numbers divided into four _-bit values called octets, each octet can have a value from _ to ___
A
IP addresses are 32-bit numbers divided into four 8-bit values called octets, each octet can have a value from 0 to 255
2
Q
Subnet masks are also __-bit numbers, that serve to determine how many bits are allocated to a ___ __, and how many are allocated to a ___ __
A
Subnet masks are also 32-bit numbers, that serve to determine how many bits are allocated to a network ID, and how many are allocated to a host ID
3
Q
192.168.14.250 = 11000000.10101000.0001110.11111010 255.255.255.0 = 11111111.11111111.11111111.00000000
A
192.168.14.250 = 11000000.10101000.0001110.11111010 255.255.255.0 = 11111111.11111111.11111111.00000000
4
Q
How is the subnet mask used to determine the network ID?
A
Computers determine the network ID by doing a logical AND operation between its IP address and subnet mask. A logical AND is an operation between two binary values. AND operations can have the following results: 0 AND 0 = 0 1 AND 0 = 0 0 AND 1 = 0 1 AND 1 = 1 The logical AND operation between a computer’s IP address and subnet mask looks like this: 10101100.00011111.01100100.00000110 (binary for 172.31.100.6) AND 11111111.11111111.00000000.00000000 (binary for 255.255.0.0) ____________________________ 10101100.00011111.00000000.00000000 (binary for 172.31.0.0)
5
Q
How do i convert 125 from Decimal to Binary
A
To convert 125 to binary use the following chart and follow the directions: 128_64_32_16_8_4_2_1 0___1__1___1__1_1_0_1 125 is less than 128, so you place a 0 in the column under the 128. The test number remains 125 125 is greater than 64, so you place a 1 in the column under the 64 and subtract 64 from 125, leaving your new test number as 61 61 is greater than 32, so you place a 1 in the column under the 32 and subtract 32 from 61, leaving your new test number as 29 29 is greater than 16, so you place a 1 in the column under the 16 and subtract 16 from 29, leaving your new test number as 13
6
Q
Converting Binary to Decimal the Simplest way: 11010011
A
Using the binary number 11010011, you get the following: 128+64+0+16+0+0+2+1 = 211
7
Q
What is IP Address class A
A
- Value of the first octet is between 1 and 127
- IP registry assigns the first octet, leaving the last three octets to be assigned to hosts
- Intended for large corporations and government
8
Q
What is IP Address class B
A
- Value of the first octet is between 128 and 191
- IP registry assigns the first two octets, leaving the third and fourth octets to be assigned to hosts
- Intended for use in medium to large networks
9
Q
What is IP Address class C
A
- Value of the first octet is between 192 and 223
- IP address registry assigns the first three octets
- These networks are limited to 254 hosts per network
- Intended for small networks
10
Q
What is IP Address class D
A
- Value of the first octet is between 224 and 239
- reserved for multicasting
11
Q
What is IP Address class E
A
- Value of the first octet is between 240 and 255
- Reserved for experimental use and can’t be used for address assignment
12
Q
What are reserved addresses?
Which addresses are reserved?
A
Addresses that can’t be routed except for the specific entities that have them reserved.
- Class A addresses beginning with 10
- Class B addresses from 172.16 to 172.31
- Class C addresses from 192.168.0 to 192.168.255
13
Q
What is a link-local address
A
- Not assigned locally or through DHCP
- Assigned automatically when a computer is configured to receive an IP address through DHCP but no DHCP service is available
14
Q
What is Automatic Private IP Addresssing (APIPA)
A
- This is another term for a link-local address
- assigned in the range of 169.254.1.0 through 169.254.254.255 with a subnet mask of 255.255.0.0
15
Q
What is Classless Interdomain Routing (CIDR)
A
The use of IP addresses without requiring the default subnet mask
16
Q
what is Classful addressing
A
The use of IP addresses with their default subnet masks
17
Q
With CIDR if the IP address is 172.31.210.10 and the subnet mask is 255.255.255.0 what is the host ID?
A
.10
18
Q
What is the format for CIDR notation
A
A.B.C.D/n where n is the number of 1 bits in the subnet mask
19
Q
Express 172.31.210.10 with a subnet mask of 255.255.255.0 as a CIDR notation
A
172.31.210.10/24
The network ID is 24 bits, leaving 8 bits for the host ID
20
Q
What does a broadcast domain define
A
which devices must receive a packet that is broadcast by another device inside the domain
21
Q
TCP/IP communication relies heavily on broadcast packets, specifically which two protocols?
A
DHCP and ARP which both use broadcasts to perform their tasks
22
Q
What is subnetting
What are the reasons to subnet
A
A process that reallocates bits from an IP address’s host portion to the network portion, creating multiple smaller address spaces
- To divide a very large network into many smaller subnetworks
- To conserve IP addresses
- To divide a network into smaller groups
23
Q
What is the process for subnetting
A
- Decide how many subnets you need. Each router interface connection indicates a required subnet
- Decide how many bits you need to meet or exceed the number of required subnets
- Use the formula 2^n with n representing the number of bits you must reallocate from the host ID to the network ID
- The number of subents you create is always a power of 2, so if you need 60 subnets, you must must reallocate 6 bits (2^6 = 64) because reallocating 5 bits gives you only 32 subnets
24
Q
What is supernetting
A
- This is the process of reallocating bits from the network portion of an IP address to the host portion
- Making two or more smaller subnets a larger supernet
- Also known as route aggregation or route summarization
25
Rules for IPv4 Address assignment
* A host can be assigned only a Class A, Class B, or Class C address
* Every IP address configuration must have a subnet mask
* All hosts on the same physical network must share the same network ID in their IP addresses
* All host IDs on the same network must be unique
* You can't assign an IP address in which all the host ID bits are binary 0
* You can’t assign an IP address in which all the host ID bits are binary 1
* Computers assigned different network IDs can communicate only if a router is present to forward packets
* The default gateway address assigned to a computer must have the same network ID as that computer
26
Windows OSs allow multiple IP addresses to be assigned to a single network connection, via advanced TCP/IP settings box.
Why might multiple IP addresses be useful?
* The computer is hosting a service that must be accessed by using different addresses
* The computer is connected to a physical network that hosts multiple IP networks
27
What is a multihomed server?
What are the reasons for using this type of configuration?
* A server that has two or more NICs, each attached to a different IP network
* Each NIC requires its own IP address for the network to which its connected
Reasons for this configuration include:
* A server is accessed by internal clients and external clients
* A server provides resources for computers on multiple subnets of the network
* A server is configured as a router or VPN server
28
What does typing the route print command prompt do?
displays the routing table and five columns of results:
Network Destination, Netmask, Gateway, Interface, Metric
29
What is the netsh.exe command
This command can be used for many tasks such as firewall and IP address configuration
To see a list of netsh commands, type: netsh /?
30
what is ipconfig
usually used to display a computers IP address settings but it can perform other tasks including:
* /all
* /release
* /renew
* /displaydns
* /flushdns
* /registerdns
31
what does ping do
* used to test connectivity between two computers by sending an ICMP echo request packet
* If the destination receives the packet and is able to respond it will do so with an ICMP echo reply packet
* to see all available options for the ping command type ping /?
32
what does arp do?
The arp command displays or makes chagnes to the Address Resolution Protocol (ARP) cache, which contains IP address - MAC address pairs
Can add static ARP entries
Some options for ARP command:
* -a, -g: displays current ARP entries
* -d: deletes ARP entries
* -s: adds a static ARP entry
33
what is tracert
* usually called "trace route" because it displays the route packets take between two computers
* works by sending out packets with a total TTL value starting at 1 and increases the value until the destination is reached
* Useful for troubleshooting the routing toplogy of a complex network and finding bottlenecks
* Displays the time it took to receive a reply from each router (could indicate where bottlenecks might be)
34
what does nslookup do?
* Used to test and troubleshoot DNS operation
* Can be used in command mode or interactive mode
* In command mode, you type nslookup host to query for the host's address
* In interactive mode, you can simply type host to get the host's address
* Typinga question mark at the interactive mode prompt gives a list of available options
35
What is NAT and what does it do
Network Address Transition
* NAT allows an organization to use private IP addresses while connected to the internet
* The NAT process translates a workstation’s private address (as a packet leaves the corporate network) into a valid public Internet address
* When data returns to the workstation, the address is translated back to the original private address
* Nat is usually handled by a network device connected to the Internet, such as a router
* Address translation is kept track of in a NAT table
36
What is PAT
Port Address Translation (PAT)
* Allows several hundred workstations to access the Internet with a single public Internet address
* Each packet contains source and destination IP addresses along with source and destination port numbers
* A single public IP address is used for all workstation, but different source port numbers are used for each communication session
37
What is the improvements made by IPv6
* Larger address space
* Hierarchical address space
* Autoconfiguration
* Built-in Quality of Server (QoS) support
* Built-in support for security
* Support for mobility
* Extensibility
38
How many bits are IPv6 addresses and how are they structured
128 bits, written as eight 16-bit hexadecimal numbers separated by colons
One or more consecutive 0 values can be written as a double colon, but only one double colon can exist in an IPv6 address
Leading 0's are optional
Hexadecimal numbers are easier to convert to binary
39
The interface ID of an IPv6 is typically how many bits
64
What is the autoconfigured 64-bit host ID referred to as? an Extended Unique Identifier (EUI) - 64 interface ID
The IPv6 address is entered manually in the inerface's Properties dialog box
40
IPv6 defines what 3 address types?
* Unicast
* Multicast
* Anycast
41
What is a Loopback address
This is a special purpose IPv6 address that is equivalent to 127.0.0.1 used in IPv4 and is written as ::1
42
What is a Zero address
This is a Special Purpose IPv6 address that is used as a placeholder in the source address field of an outgoing IPv6 packet and is written as ::
43
What is a documentation address
This is a IPv6 Special Purpose address. the global unicast address 2001:db8::/32 has been reserved for use in books and other documentation discussing IPv6
44
What is the structure breakdown for a typical IPv6 address
Global routing prefix (48 bits), Subnet ID (16 bits), Interface ID (64 bits)
45
How do IPv6 Unicast addresses work?
* Link-local - addresses starting with fe80, are self-configuring, and can't be routed (used for computer-to-computer communication)
* Unique local - addresses starting with fc or fd that are for use behind a firewall and are preconfigured on routers
* Global - accessible on the public internet and can be routed
46
How do IPv6 Multicast addresses work?
* same function as its counterpart in IPv4
* Begin with ff and havethe following structure
* ffxy:zzzz:zzzz:zzzz:zzzz:zzzz:zzzz:zzzz
* flags - 4bit field, indicated by the x, uses the three low-order bits
* Scope - indicated by the y, specifies whether and where the multicast packet can be routed
* Group ID - represented by the z characters, identifies a multicast group
47
How do IPv6 Anycast addresses work?
* can be assigned to multiple interfaces on different nodes
* Are recognized as anycast addresses only by the devices that use them
* Are assigned on routers and are used to allow other IPv6 nodes to deliver packets to the nearest router on a subnet
* don't have a special format
48
IPv6 autoconfiguration occurs by two methods
* Stateless autoconfiguration
* the node listens for router advertisement messages from a local router
* Stateful autoconfiguration
* the node uses an autoconfiguration protocol, such as DHCPv6, to obtain its IPv6 address and other configuration information
49
What are the Windows autoconfiguration steps?
1. At initialization, a link-local address id determined
2. The link-local address is verified as unique by using duplicate address detection
3. If the address is verified as unique, the address is assigned to the interface
4. The host transmits a router solicitation message
5. If no router advertisement messages are received in response to the solicitation message, the host attempts to use DHCPv6 to get an address
6. If router advertisement message is received, the prefix in the router advertisement is used along with the interface ID to configure the IPv6 address on the interface
50
What is IPv6-over-IPv4 Tunneling?
a network protocol technique that allows transmitting a packet in a format that's otherwise incompatible with the network architecture by encapsulating the packet in a compatible header format
51
What is Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
this is used to transmit IPv6 packets between dual IP layer hosts across an IPv4 network
ISATAP addresses have the following format:
Fe80::5efe:n:n:n:n
52
What is "Teredo" tunneling
* an automatic IPv6-over-IPv4 tunneling protocol that solves the problem of 6to4's requirement of a public IPv4 address
* and the inability to traverse NAT routers
* Teredo has three components
* Teredo client
* Teredo server
* Teredo relay
* A teredo address can be identified by the Teredo prefix 2001::/32
53
What are protocols
* Protocols are rules and procedures for communication and behavior
* computers must "speak" the same language and agree on the rules of communication
54
What is it called when a set of protocols works cooperatively?
What is the most common example of this?
Protocol suite or protocol stack
Transmission Control Protocol/Internet Protocol (TCP/IP)
55
What are the four layers of TCP/IP protocols
* Application
* Http, FTP, DHCP, TFTP, SMTP, POP3, DNS, SNMP
* Transport
* TCP, UDP
* Internetwork
* ICMP, ARP, IPsec, IPv4 and IPv6
* Network access
* Ethernet, token ring, FDDI, WAN technologies
56
What is the unit of information used by the application layer known as?
"data"
57
What is the unit of information the transport layer works with called?
a segment
58
what does the application layer provide
* network services to user applications that access network resources
* with most application layer protocols, both a client and a server version exist
the following functions:
* Access by applications to network services
* Client/server data access
* Name resolution
* Dynamic address assignment
* Authentication/user logon
* Data formatting and translation
59
What was the original purpose of HTTP and what is it's main purpose now?
What transport layer protocol does it use
What is the default port number
Originally used to transfer static web pages written in HTML
Now its used for general file transfer and downloading/displaying multimedia files
TCP
default port number is 80
60
What is Post Office Protocol version 3 (POP3) used for?
to download incoming messages from e-mail servers to local desktops (uses TCP port 110)
61
What is Internet Message Access Protocol v.4 (IMAP4) used for?
to manage email messages locally yet store them on a server (uses TCP port 143)
62
What is Simple Mail Transfer Protocol (SMTP) used for?
the standard protocol for sending email over the internet (uses TCP port 25)
63
What is File Transfer Protocol (FTP)
* FTP is a client/server protocol used to transfer files
* Uses TCP ports 20 and 21
* Port 20 is for users sending control commands
* port 21 is for transferring file data
* Not a secure protocol
64
What is Trivial File Transfer Protocol (TFTP)
* is a simple protocol for transferring files
* Has little file management capability
* Uses UDP port 69
65
What is the Server Message Block (SMB)
* the protocol Windows file and printer services use to share resources between Windows computers
* Used almost exclusively in a private network instead of accross the Internet
* Uses TCP port 445
* Linux and Mac OS X also support SMB with their own variations
66
What is Remote Desktop Protocol (RDP)
* used to access a Windows computer remotely by using the Windows GUI
* used to run windows applicatons remotely and network administrators use it to manage windows workstations and servers remotely
67
What is Telnet and Secure Shell (SSH)
* Telnet and Secure Schell (SSH)
* Used to connect a device across a network via a command-line interface
* Example: use to connect to a managed switch or router
* Telnet uses TCP port 23
* Is not a secure protocol
* SSH uses TCP port 22
* Provides an encrypted channel between the client and server
68
What is Simple Network Management Protocol
* SNMP is used to monitor and manage network devices and gather statistics about network traffic
* Software agents are installed on devices you want to monitor and manage
* Agents collect data and transfer it to a network management station for storage and analysis
* SNMP operates on UDP ports 161 and 162
69
What is Dynamic Host Configuration Protocol (DHCP)
* DHCP is a way to automatically assign IP addresses as needed
* When a computer is turned on, it requests an address from a server that is configured as a DHCP server
* The server assigns an address for a specific amount of time (called a lease)
70
What is a DHCP server composed of?
* IP address scope - a range of IP addresses the server leases to clients
* Scope options - IP settings such as default gateway, DNS servers, a domain name, and other options
* Reservations - an IP address tied to a particular MAC address
* Exclusions - one or more IP addresses excluded from the IP address scope
* DHCP Server service - runs in the background and listens on UDP port 69 for IP address requests
71
What happens on a DHCP server after an address is leased?
* A record of the lease is stored in a database, including a lease expiration time
* When 50% of the lease time has elapsed, the computer attempts to renew the lease from the same DHCP server that originally responded
* If no response, the computer waits until lease is 87.5% expired, a broadcast DHCP renewal request is sent
* if no response when lease expires, computer broadcasts a DHCP request for a new IP address
72
Why does DHCP use UDP
DHCP servers are usually located on the same network and DHCP messages are short
73
What are the four broadcast packets used by the DHCP process?
* DHCPDiscover
* the client announces to the network that it's looking for a DHCP server
* DHCPOffer
* the server replies and offers the client an IP address for lease
* DHCPRequest
* the client wants the offered IP address
* DHCPAck
* the server acknowledges the transaction and the client can now use the IP address
74
What is a Domain Name System (DNS)
* DNS is a name-to-address resolution protocol that keeps a list of computer names and their IP addresses
* Using DNS a user can use a computer's name instead of using it's IP address
75
how is DNS organized?
What is a fully qualified domain name (FQDN)
in a treelike hierarchy
When you put all the names of a branch together, seperated by periods
76
Describe each of the following domains:
Top-level
Second-level
Subdomain
Host level
* level domains are organized into categories such as commercial (.com), nonprofit organizations (.org), goverment (.gov) or country of origin indicated by a two-letter code
* second-level domains are usually the name of a company or institution
* subdomain is optoinal and can consist of names separated by a period
* host level represents individual computers hosting network services
77
What does DNS client do
The DNS client is responsible for communicating with a DNS server to resolve computer and domain names to IP addresses
referred to as a "resolver"
78
DNS servers are composed of the following:
DNS zones
Resource records
Cache
Root hints
DNS Server service
* DNS zones - a database of primarily hostname and IP address pairs
* Resource records - the data contained in a zone
* Cache - results of queries are cached so that if the same query occurs again, the local DNS server can respond without having to contact another server
* Root hints - file containing a list of all IP addresses of Internet root servers
* DNS Server service - runs in the background and listens for DNS queries on UDP port 53
79
Why are transport-layer protocols used with most Application-layer protocols
* supply a header field to identify the Application layer
* provide reliability and flow control for applications that typically transfer a large amount of data
80
What are the two protocols found in the transport layer
* Transmission Control Protocol (TCP)
* Connection oriented and designed for reliable transfer of information in complex internetworks
* User Datagram Protocol (UDP)
* Connectionless and designed for efficient communication of generally small amounts of data
81
What are the differences between the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) and what is true of both
* TCP is connection oriented and designed for reliable transfer
* UDP is connectionless and designed for efficient communication of very small amounts of data.
* Both
* Work with segments or datagrams
* Provide a means to identify the source and destination applications involved in a communication
* Protect data with a checksum
82
What are the two main purposes of IP addresses
* to identify a network device at the internetwork layer
* to identify the network on which a device resides
83
What are the internetwork-layer protocols primarily focused on?
* efficient delivery of packets
* features such as flow control, delivery confirmation or message assembly are not included
* these features require overhead to ensure reliable delivery
* rely on the protocols in the transport and application layers to provide reliability features
* Considered a connectionless protocol - relies on upper-layer protocols to ensure the packet's safe journey
84
What are the four main tasks done by the internetwork-layer protocols
* Defines and verifies IP addresses
* Routes packets through an internetwork
* Resolves MAC addresses from IP addresses
* Delivers packets efficiently
85
What does the Internetwork layer determine
* the best way to get a packet from network to network until it reaches its destination
* Routers work at the Internetwork layer and it is their job to select the best path to the destination
* Routers use the network ID portion of IP addresses along with their routing tables to determine the best path
86
What do internetwork-layer protocols primarily focus on?
* Efficient delivery of packets
* features such as flow control, delivery confirmation or message assembly are not included
* Rely on the protocols in the Transport and Application layers to provide reliability features
* Considered a connectionless protocol - relies on uppper-layer protocols to ensure the packet's safe journey
87
What are the important fields in an IP packet?
* Version
* Time to live (TTL)
* Protocol
* Checksum
* Source and Destination address
88
What is an ARP cache
* This is a temprorary location in RAM where PCs and other devices store learned IP addresses so it doesn't have to send an ARP request every time
* If the destination computer is on another network:
* The computer uses ARP to retrieve the MAC address of the router configured as its default gateway
* The packet is delivered to the router and the router determines where the packet should go next to get to its destination
89
What is an Internet Control Message Protocol used for?
* to send error and control messages between systems or devices
* specialized IP packet with its own header
* A ICMP Reply indicates whether the host is reachable and how long the message's round trip from sender to receiver took
90
What do Network Access-Layer Protocols do
* Provides a physical (MAC) address for the network interface
* verifies incoming frames have the correct destination MAC address
* Defines and follows media access rules
* Provides frame error detection (a CRC code)
* transmits and receives bit signals
* defines the signaling needed to transmit bits, whether electrical, light pulses, or radio waves
* defines the media and connectors needed to make a physical network connection
Introduction to Networking
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