IPv4 (Internet Protocol version 4) is the fourth version of the Internet Protocol and the most widely deployed protocol for identifying devices on IP networks.

An IPv4 address is a 32-bit number that uniquely identifies a network interface.

Example:

203.0.113.25

Although IPv6 has been introduced, IPv4 remains the dominant protocol on today's Internet.

An IPv4 address consists of 32 bits divided into four groups of eight bits (called octets).

Example:

203.0.113.25

↓

11001011.00000000.01110001.00011001

Each octet can have a value between:

0 – 255

Therefore an IPv4 address is written as:

x.x.x.x

where each x is between 0 and 255.

A 32-bit address provides:

2^32

=

4,294,967,296

possible addresses.

Although this seems like a large number, it is no longer sufficient for today's Internet.

This shortage led to the development of IPv6.

IPv4 addresses are divided into:

• Public addresses
• Private addresses

Public addresses are globally routable on the Internet.

Private addresses are used within local networks and are translated to public addresses through Network Address Translation (NAT).

See also:

• Private vs Public IP
• Network Address Translation (NAT)

An IPv4 address consists of two logical parts:

• Network portion
• Host portion

Example:

192.168.1.25/24

Network:
192.168.1

Host:
25

The boundary between the network and host portions is determined by the subnet mask or CIDR prefix.

Some IPv4 addresses have special purposes.

These addresses are reserved and cannot always be used as ordinary public addresses.

The number of available IPv4 addresses is limited.

As Internet usage grew, the supply of public IPv4 addresses became exhausted.

Several technologies help reduce IPv4 consumption:

• NAT
• Private addressing
• CIDR
• Dynamic address allocation (DHCP)

Ultimately, IPv6 was developed to overcome this limitation.

An IPv4 address can provide useful information such as:

• Whether it is public or private.
• Geographic location (approximate).
• ASN (Autonomous System Number).
• Reverse DNS (PTR).
• Network owner.

Several Telenegar tools work with IPv4 addresses.

• IP Check
• Ping Check
• Traceroute
• Port Check

These tools can help identify ownership, routing, connectivity, and DNS information associated with an IPv4 address.

• Every IPv4 address is publicly accessible.
  • False. Many IPv4 addresses are private and cannot be reached directly from the Internet.

• IPv4 is obsolete.
  • False. Although IPv6 is growing, IPv4 remains the most widely used Internet Protocol.

• An IPv4 address identifies a person.
  • False. It identifies a network interface, not an individual.

• IP Addresses
• IPv6
• Private vs Public IP
• Subnetting
• CIDR Notation
• Network Address Translation (NAT)
• IP Check

ipv4 ip internet networking cidr subnet nat