An IP (Internet Protocol) address is a unique numerical identifier assigned to a device connected to an IP network.

Just as every house has a postal address, every device communicating over the Internet or a local IP network requires an IP address.

IP addresses allow data to be delivered to the correct destination.

When you access a website, send an email, or use an online application, information is exchanged as small packets.

Each packet contains:

• Source IP address
• Destination IP address

Routers use these addresses to determine where each packet should be sent.

Without IP addresses, Internet communication would not be possible.

Imagine sending a letter through the postal service.

The envelope contains:

• Sender's address
• Recipient's address

Similarly, an IP packet contains:

• Source IP address
• Destination IP address

Letter

From:
Tehran

To:
London

↓

IP Packet

Source:
192.0.2.15

Destination:
93.184.216.34

Two versions of the Internet Protocol are currently in use.

IPv4 remains the most widely used protocol, while IPv6 was introduced to overcome IPv4 address exhaustion. :contentReference[oaicite:0]{index=0}

IP addresses fall into two broad categories.

A public IP address is globally unique and can be reached over the Internet.

Examples:

8.8.8.8
1.1.1.1
93.184.216.34

Public addresses are allocated through Internet registries and Internet Service Providers.

Private IP addresses are used only within local networks and are not routed across the public Internet.

The three IPv4 private ranges defined by RFC 1918 are: :contentReference[oaicite:1]{index=1}

Home and office networks commonly use these addresses.

An IP address may be:

• Static – permanently assigned.
• Dynamic – assigned temporarily, usually by DHCP.

Most home Internet connections use dynamic public IP addresses.

Servers often use static addresses.

Humans prefer names such as:

example.com

Computers communicate using IP addresses:

93.184.216.34

DNS (Domain Name System) translates domain names into IP addresses.

example.com
      │
      ▼
93.184.216.34

A device may have more than one IP address.

Examples:

• IPv4 and IPv6 simultaneously
• Multiple network interfaces
• Virtual IP addresses
• VPN connections

Likewise, a single IP address may host multiple websites through virtual hosting.

Yes.

An IP address may change because of:

• DHCP lease renewal
• ISP reassignment
• VPN usage
• Moving to another network

For this reason, many services rely on domain names instead of hard-coded IP addresses.

An IP address is only one part of Internet communication.

Other important concepts include:

• Subnet Mask
• Default Gateway
• DNS
• MAC Address
• NAT

These topics are covered separately in this documentation.

Several Telenegar tools use IP addresses, including:

• IP Check
• Ping Check
• Traceroute
• Port Check

These tools help investigate routing, connectivity, ownership, and network configuration.

• Every device has a public IP address.
  • False. Most devices use private IP addresses behind a router.

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

• A website has only one IP address.
  • False. Many websites use multiple IPv4 and IPv6 addresses, load balancers, or CDNs.

• DNS Explained
• IPv4
• IPv6
• Network Address Translation (NAT)
• IP Check

ip ipv4 ipv6 networking public-ip private-ip