IP Addressing Flashcards by Kelvin Castillo

An assigned numerical label that is used to identify internet communicating devices on a computer network |
Layer 2
Addressing
Between two devices that are internal to own network or LAN

Internet Protocol (IP) Address

How well did you know this?

Not at all

Perfectly

Layer 3
Addressing

Between two different networks or subnets

How well did you know this?

Not at all

Perfectly

A unique number that identifies a device on a network.

IP Address

How well did you know this?

Not at all

Perfectly

IP addresses work at Layer 3 (Network Layer).

Network Layer

How well did you know this?

Not at all

Perfectly

Used inside your local networks (Layer 2)

MAC

How well did you know this?

Not at all

Perfectly

Used to send data between networks

IP (Layer 3)

How well did you know this?

Not at all

Perfectly

like a home address for a device.

House number, street, city → tells routers where to send data.

Routers = post offices, sending “mail” (data) from one network to another.

IP address

How well did you know this?

Not at all

Perfectly

What is an IPv4 address?

How well did you know this?

Not at all

Perfectly

What is an octet in IPv4?

Each of the four numbers in an IPv4 address, representing 8 bits.

How well did you know this?

Not at all

Perfectly

How is an IPv4 address divided?

Into a network portion (identifies the network) and a host portion (identifies a specific device).

How well did you know this?

Not at all

Perfectly

What is a subnet mask?

A 32-bit number that separates the network portion from the host portion of an IPv4 address.

How well did you know this?

Not at all

Perfectly

What does a subnet mask of 255.255.255.0 mean?

The first three octets (24 bits) are the network portion, and the last octet (8 bits) is the host portion.

How well did you know this?

Not at all

Perfectly

What are the five IPv4 classes?

A (1–127), B (128–191), C (192–223), D (224–239, multicast), E (240–255, experimental).

How well did you know this?

Not at all

Perfectly

How many hosts can a class A, B, or C network have?

Class A: ~16.7 million, Class B: 65,536, Class C: 256 hosts.

How well did you know this?

Not at all

Perfectly

What is a classful subnet mask?

The default subnet mask for an IPv4 class (A: /8, B: /16, C: /24).

How well did you know this?

Not at all

Perfectly

What is a classless subnet mask?

Any subnet mask that differs from the default, used in CIDR notation (e.g., /26 instead of /24).

How well did you know this?

Not at all

Perfectly

How do you write an IPv4 address with CIDR notation?

By adding a slash and the number of network bits (e.g., 192.168.1.4/24).

How well did you know this?

Not at all

Perfectly

A logical identifier for a group of hosts in a computer network

Multicast Address

How well did you know this?

Not at all

Perfectly

First number: 1–127

Subnet mask: 255.0.0.0 → 1 part network, 3 parts devices

Can have ~16.7 million devices

Class A

How well did you know this?

Not at all

Perfectly

First number: 128–191

Subnet mask: 255.255.0.0 → 2 parts network, 2 parts devices

Can have 65,536 devices

Class B

How well did you know this?

Not at all

Perfectly

First number: 192–223

Subnet mask: 255.255.255.0 → 3 parts network, 1 part device

Can have 256 devices

Class C

How well did you know this?

Not at all

Perfectly

First number: 224–239

No subnet mask → used for multicast (sending to a group)

Class D

How well did you know this?

Not at all

Perfectly

First number: 240–255

No subnet mask → reserved for future or experimental use (~268 million addresses)

Class E

How well did you know this?

Not at all

Perfectly

It’s basically:

A = huge network

B = medium network

C = small network

D = group messages

E = experiments/future

How well did you know this?

Not at all

Perfectly

The process of taking a larger network portion and subdividing it into a smaller portions | Classful & Classless

Subnetting

Default subnet mask for a given class of IP addresses

Classful Mask

Used to borrow some of the host bits from an IPv4 address

Classless Mask

Classless Inter-Domain Routing Notation

CIDR Notation

What does a subnet mask do?

It splits an IP address into network and host parts.

Q: What are the first number ranges for Class A, B, and C networks?

A: 1–127 B: 128–191 C: 192–223

What is Class D used for?

Multicast (sending to a group).

What is Class E used for?

A: Experimental or future use.

What is CIDR notation?

A shorter way to show an IP and subnet mask (example: 192.168.1.4/24).

Network and Host Portions

Every IPv4 address is split into two parts: Network portion – identifies the network. Host portion – identifies the device on that network. This split is decided by another 32-bit number called a subnet mask. Example: 255.255.255.0

Class D (Multicast)

Used for sending data to multiple devices at once, like a group chat. Example: one message sent to the group address, and all group members receive it.

Class E (Experimental)

Used only for research and future testing.

Subnetting

Subnetting = splitting a big network into smaller ones. Two types: Classful subnetting → uses the default subnet mask for its class. Classless subnetting → uses a custom subnet mask (different from default).

Why Classless Subnets Are Used

Classful networks are often too large. You don’t need millions of addresses for a small network. So, we can borrow bits from the host portion to make more networks and fewer hosts.

What range of numbers does Class A start with?

1–127.

What is the default subnet mask for Class A?

255.0.0.0.

How many devices can a Class A network have?

About 16.7 million.

What are Class A networks used for?

Very large networks.

What range of numbers does Class B start with?

128–191.

What is the default subnet mask for Class B?

255.255.0.0.

What are Class B networks used for?

Medium-sized networks.

How many devices can a Class B network have?

65,536 devices.

What is the default subnet mask for Class C?

255.255.255.0.

Q: What range of numbers does Class C start with?

A: 192–223.

How many devices can a Class C network have?

256 devices.

What are Class C networks used for?

Small networks.

What range of numbers does Class D start with?

224–239.

What is Class D used for?

Multicasting (sending to a group).

What range of numbers does Class E start with?

240–255.

What is Class E used for?

Experimental or research purposes.

Unique IP address assigned to each device on the Internet that allows it to communicate with other devices using IPv4

Public (Routable)

How are public addresses written?

In dotted decimal notation and divided into four octets (e.g. 66.51.24.12)

Globally manages and leases publicly routable IP addresses

Internet Corporation for Assigned Names and Numbers (ICANN)

Private IP Ranges

10 - 10.X.X.X 172 - 172.16.X.X 192 - 192.268.1.X

Used within a local network that allows for the communication between devices within that network without using a public IP address

Private (Non-Routable)

Method used in networking that allows a single device to act as an agent between the Internet (public network) and a local network (private) | It converts or translates a private IP into a public IP and then back again on behalf of your system

Network Address Translation (NAT)

Formal publication from the Internet Society and the Internet Engineering Task Force (IETF)

Request for Comments (RFCs)

Class A Starting Value 10 IP Range - 10.0.0.0-10.255.255.255 Possible Hosts - 16.7 million (256 x 256 x 256) Class B Starting Value - 172.16-172.31 IP Range - 172.16.0.0-172.31.255.255 Possible Hosts - 1.05 million Class C Starting Value - 192.168 IP Range - 192.168.0.0- 192.168.255.255 Possible Hosts - 65,536

Specialized IP address assigned as 127.0.0.1

Loopback Address (Localhost)

Addresses that are assigned by the OS when the network's DHCP server is unavailable and an IP address has not been statically assigned by the system

Automatic Private IP Addresses (APIPA)

What is the APIPA Range?

169.254.0.0 to 169.254.255.255 DHCP problem

Unique global identifiers to communicate over the Internet and are managed by ICANN and its regional bodies

Public

Used within local networks and allow for internal communication without being directly exposed to the Internet

Private

Used for internal testing of the device's network protocols

Loopback (Localhost)

Fallback for network configurations when DHCP fails, but are considered private IPs

Automatic Private IP Address (APIPA)

Loopback address creates a loopback to the host and is often used for troubleshooting and testing the network protocol softtware on a system

Data travels from a single source device to a single destination device one-way conversation

Unicast

Data travels from a single source device to multiple (but specific) destination devices

Multicast Only those who opted to get it

Data travels from a single source device to all device on a destination network

Broadcast Everybody

Manually typing in the IP address for the host, its subnet mask, default gateway, and DNS server | impractical on large enterprise networks

Static Assignament

Dynamic allocation of IP addresses | DHCP, APIPA, ZeroConf

Dynamic Assignment

Most SOHO network devices already run a DHCP server and is turned on by default

Identifies NetBIOS systems on a TCP/IP network and converts those NetBIOS to IP address | WINS is like DNS, but it only works within a Windows domain environment

Windows Internet Name Service (WINS)

Converts the domain names used by a website to the IP address of its server the internet's version of the phone book names to numbers and numbers to names

Domain Name System (DNS)

Assigns an IP based on an assignable scope or pool of addresses and provides the ability to configure numerous other options within it | IP address, subnet mask, default gateway, DNS,WINS server

Dynamic Host Configurations Protocol (DHCP)

Used when a device does not have a static IP address or cannot reach a DHCP server | APIPA-assigned devices cannot communicate outside the LAN or with non-APIPA devices

Automatic Private IP Addressing (APIPA)

A newer technology based on APIPA which provides a lot of the same features and some new ones

Zero Configuration (ZeroConf)

s = number of borrowed bits

Created subnets

/25

2^1 = 2 subnets 1 = number of borrowed bits

Assignable IP Address

2^h - 2 h = number of host bits

/25

2^7 - 2 32 total - 25 networks = 7 host

Every network out there has to have two IP addresses to be a network

Network ID Broadcast ID

Assignable IP Address

2^h - 2 h = number of host bits

Shorthand notation used to summarize continuous networks called using aggregation

Classless Inter-Domain Routing (CIDR)

Allows subnets of various sizes to be used and requires a protocol that supports it | is a subnetting of subnets

Variable-Length Subnet Mask (VLSM)

CIDR Subnets IPs /24 1 256 /25 2 128 /26 4 64 /27 8 32 /28 16 16 /29 32 8 /30 64 4

What is subnetting?

Subnetting splits one large network into smaller, efficient sub-networks.

Why is subnetting important?

It saves IP addresses, improves security, and helps manage network traffic.

Q: What is the default subnet mask for Class A?

A: /8 or 255.0.0.0

Q: What is the default subnet mask for Class B?

A: /16 or 255.255.0.0

Q: What is the default subnet mask for Class C?

A: /24 or 255.255.255.0

Q: What does “borrowing bits” mean in subnetting?

A: Taking bits from the host portion to make more network portions.

Q: Formula to find number of subnets?

A: 2^s, where s = number of bits borrowed.

Q: Formula to find number of usable hosts?

A: 2^h – 2, where h = number of host bits.

Q: Why do we subtract 2 in the host formula?

A: One IP is for the network ID, and one for the broadcast address.

Q: Example: How many usable IPs in a /25 subnet?

A: 126 usable IPs (2^7 – 2).

Q: What’s a classful network?

A: One that uses default subnet masks like /8, /16, or /24.

Q: What’s a classless network?

A: One that uses custom subnet masks, like /25–/30.

Q: What is CIDR notation used for?

A: To represent a network’s subnet mask with a slash number (e.g., /24).

Q: What is VLSM?

A: Variable-Length Subnet Masking — allows subnets of different sizes.

Q: Why use VLSM?

A: To assign subnet sizes based on department or device needs.

Q: How do you find the network and broadcast addresses?

A: Network = first address in range; Broadcast = last address in range.

Q: How do you find the first and last host addresses?

A: First host = network + 1; Last host = broadcast – 1.

What are the benefits of IPv6?

Larger address space, no broadcasts, no fragmentation, simplified header

Used to identify a single interface - Globally-routed & Link-local

Unicast address

Similar to IPv4's unicast class, A, B, and C addresses and begins with 2000-3999

Globally-routed

Used like a private IP in IPv4 that can only be used on the local area network and begins with FE80

Link-local/Local Use

Eliminates the need to obtain addresses or other configuration information from a central server - EUI-64 & NDP

Stateless Address Autoconfiguration (SLAAC)

Used to identify a set of interfaces and begins with FF

Multicast Address

Used to identify a set of interfaces so that a packet can be sent to any number of a set

Anycast Address

Allows a host to assign itself a unique 64-bit IPv6 interface identifier called EUI-64

Extended Unique Identifier (EUI)

Allows DHCP to automatically assign addresses from a DHCPv6 server

DHCPv6 Protocol

Used to determine the Layer 2 addresses that are on a given network - Router solicitation, router advertisement, neighbor solicitation, neighbor advertisement, redirection

Neighbor Discovery Protocol (NDP)

Ipv6 addresses 128 bits shorthand notation and zero compression ipv6 is written in hexadecimal, not in decimal unicast multicast anycast

ipv4 addresses 32 bits

A message is sent to a group, but the network delivers it to the closest device in that group. This makes communication faster and more efficient.

Anycast

Network architecture that allows the coexistence and simultaneous operation of both IPv4 and IPv6 protocols on the same network infrastructure | routers, switches, and hosts are configured to understand and process both IPv4 and IPv6 addresses

Dual Stack

Method used to enable the communication of one network protocol within another by encapsulating packets of a different protocol | involves encapsulating IPv6 packets within IPv4 packets

Tunneling

Network address translation mechanism that allows IPv6-only devices to communicate with IPv4 servers and services

NAT64

Sits at the edge of the IPv6 network | maintains a translation table to keep track of the mappings

NAT64 Gateway

Which of the following statements best reflects the compatibility requirements between IPv4 and IPv6 standards?

Dual-stack implementation enables coexistence, allowing devices to support both IPv4 and IPv6 simultaneosuly.

An organization with multiple departments requires efficient use of IP addresses for its network infrastructure. The network administrator is tasked with subnetting to accommodate varying numbers of hosts in different departments. Which networking technique would be most suitable for this scenario?

Variable Length Subnet Masking (VLSM)

Which of the following is a private IPv4 address?

172.16.254.10

Which type of IP address are you likely to see if a DHCP server is not working?

APIPA

In a video conferencing application, which IPv4 address class is most appropriate for multicast group communication, where data is intended to be sent to multiple recipients simultaneously?

Class D

IP Addressing Flashcards

(128 cards)