====== IP Addresses ======

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.

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===== Why Do We Need IP Addresses? =====

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.

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===== An Everyday Analogy =====

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

<code>
Letter

From:
Tehran

To:
London

↓

IP Packet

Source:
192.0.2.15

Destination:
93.184.216.34
</code>

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===== IPv4 and IPv6 =====

Two versions of the Internet Protocol are currently in use.

^ Version ^ Address Length ^ Example ^
| IPv4 | 32 bits | 203.0.113.25 |
| IPv6 | 128 bits | 2001:db8::25 |

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

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===== Public and Private IP Addresses =====

IP addresses fall into two broad categories.

=== Public IP Addresses ===

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

Examples:

<code>
8.8.8.8
1.1.1.1
93.184.216.34
</code>

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

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=== Private IP Addresses ===

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}

^ Range ^ Prefix ^
| 10.0.0.0 – 10.255.255.255 | /8 |
| 172.16.0.0 – 172.31.255.255 | /12 |
| 192.168.0.0 – 192.168.255.255 | /16 |

Home and office networks commonly use these addresses.

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===== Static vs Dynamic IP 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.

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===== Domain Names and IP Addresses =====

Humans prefer names such as:

<code>
example.com
</code>

Computers communicate using IP addresses:

<code>
93.184.216.34
</code>

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

<code>
example.com
      │
      ▼
93.184.216.34
</code>

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===== One Device, Multiple IP Addresses =====

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.

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===== Can an IP Address Change? =====

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.

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===== Related Concepts =====

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.

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===== IP Addresses and Telenegar =====

Several Telenegar tools use IP addresses, including:

  * [[tools:ipcheck|IP Check]]
  * [[tools:pingcheck|Ping Check]]
  * [[tools:traceroute|Traceroute]]
  * [[tools:portcheck|Port Check]]

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

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===== Common Misconceptions =====

  * **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.

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===== Related Topics =====

  * [[networking:dns:dns|DNS Explained]]
  * [[networking:internet:ipv4|IPv4]]
  * [[networking:internet:ipv6|IPv6]]
  * [[networking:internet:nat|Network Address Translation (NAT)]]
  * [[tools:ipcheck|IP Check]]

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{{tag>ip ipv4 ipv6 networking public-ip private-ip}}