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IP Addressing

Updated Jan 16, 2019 ·

Overview​

IP addressing is used to assign unique identifiers to devices on a network, allowing them to communicate with each other. Each IP address consists of a set of numbers that identify both the network and the specific device (host) on that network.

  • 32-bit numbers, usually represented in dotted decimal format
  • 128-bit, designed to accommodate more devices with a larger address space
  • Used for routing data packets to their correct destination across networks

Dotted Quad Notation​

Dotted quad notation is a way of representing IPv4 addresses as four decimal numbers separated by periods, each representing 8 bits of the address. For example, the IP address 192.168.1.10 is written in dotted quad notation.

  • 192.168 - network address
  • 1.10 - host address

Note: The division between the network and host address can vary, depending on the network's configuration.

Source and Destination​

Source and destination IP addresses indicate where a packet is coming from and where it is going. These addresses guide the routing of data across networks.

  • They play a crucial role in directing traffic on the internet
  • The roles can be interchanged depending on the direction of communication

IPv6​

IPv6 is the most recent version of the Internet Protocol, designed to replace IPv4. It provides a vastly larger address space to accommodate the growing number of internet-connected devices.

  • IPv6 addresses are 128-bit, represented as eight groups of four hexadecimal digits
  • No need for Network Address Translation (NAT), IPv6 provides unique address for each device
  • It includes built-in security features and improved routing efficiency

An example of an IPv6 address is:

2001:0db8:85a3:0000:0000:8a2e:0370:7334

This address is divided into eight groups of four hexadecimal digits, separated by colons. Each group represents 16 bits of the 128-bit IPv6 address.

For simplicity, leading zeros in each group can be omitted, so the address can also be written as:

2001:db8:85a3::8a2e:370:7334

The double colon (::) represents a consecutive group of zeroes that can be compressed to save space.

Types of IP Addresses​

Public IP Address​

Public IP addresses are globally unique and used for communication over the internet.

  • Assigned by ISPs and required for accessing the internet.
  • Can be static (permanent) or dynamic (temporary).
  • Exposes devices directly to the internet, requiring robust security measures.

Private IP Addresses​

Private IP addresses are used within private networks, not routable on the internet.

  • Assigned to devices within a local network (e.g., home or office).
  • Conserve public IP addresses, allows multiple devices to share one public IP via NAT.
  • Commonly used in LANs to facilitate communication within the network.

Private IP Addresses have the following types:

ClassIP RangeUsageNumber of IP Addresses
Class A10.0.0.0 - 10.255.255.255Large networksOver 16 million
Class B172.16.0.0 - 172.31.255.255Medium-sized networksOver 1 million
Class C192.168.0.0 - 192.168.255.255Small networks (e.g., home networks)Up to 65,536
Class D224.0.0.0 - 239.255.255.255Multicast groups (e.g., streaming, video conferencing)N/A

Subnetting​

Subnetting divides a large network into smaller, more manageable sub-networks (subnets).

  • Helps in managing IP address allocation within a network.
  • Enhances security by isolating network segments.
  • Optimizes network performance by reducing broadcast traffic.

For example, subnetting can be used to divide departments within an organization into separate, isolated networks.

Subnet Mask Notation​

A subnet mask is used to define which portion of an IP address is the network part and which part is the host part. It plays a crucial role in dividing networks into subnets.

  • Typically represented in dotted decimal format, like 255.255.255.0.
  • Helps in determining the size of a subnet and the number of possible hosts.
  • Essential for network routing and segmentation.

Example:

  • IP Address: 192.168.1.10
  • Subnet Mask: 255.255.255.0

Slash Notation​

Slash notation, or CIDR (Classless Inter-Domain Routing) notation, represents the subnet mask by specifying the number of bits used for the network portion.

  • Denoted as a suffix to the IP address, such as /24 for a subnet mask of 255.255.255.0.
  • Simplifies the representation of subnet masks.
  • Widely used in modern networking for efficient IP address allocation.

Example:

  • IP Address: 192.168.1.10/24