what is an ip address

What is an IP Address

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An IP address is a unique numerical identifier assigned to every device connected to a computer network that uses the Internet Protocol for communication. Think of it as a digital address for a device, allowing it to send and receive data over the internet or a local network.

An IP address is essential because it’s the fundamental way devices communicate and find each other on a network, including the internet. Without an IP address, data wouldn’t know where to go, making it impossible to send and receive information. Think of it like a unique mailing address for your device: it ensures that the information you request, like a webpage or an email, is delivered to the correct destination—your computer.

Definition

An IP address is a unique numerical identifier that must be assigned to every device in order to get connected to a network that uses the Internet Protocol (IP) for communication. It serves two main purposes: to identify the device and to provide its location on the network, which allows data to be routed to the correct destination.

An IP address has two main functions:

  • Identification: It uniquely identifies a device on a network.
  • Location Addressing: It provides the location of the device on the network, which allows data packets to be routed to the correct destination.

How IP Addresses Work

IP addresses are crucial for the internet’s functionality. When you access a website, your device sends a request containing your IP address. This request travels through various networks to the website’s server, which then sends the requested information back to your IP address. This process is managed by your Internet Service Provider (ISP), which assigns a public IP address to your network.

Who Governs IP Address

The management and allocation of IP addresses are governed by a hierarchical system. At the top is the Internet Assigned Numbers Authority (IANA), a division of the Internet Corporation for Assigned Names and Numbers (ICANN).

Here’s how the process works:

  1. IANA: IANA is the global coordinator of unique identifiers on the internet, including IP addresses. It doesn’t hand out individual addresses to users, but rather assigns large blocks of IP addresses to five Regional Internet Registries (RIRs).
  2. Regional Internet Registries (RIRs): The five RIRs are non-profit organizations that manage and distribute IP addresses within their designated geographic regions. They receive blocks of IP addresses from IANA and then allocate them to Local Internet Registries (LIRs) and other large organizations.

The five RIRs are:

  • AFRINIC: for Africa
  • APNIC: for the Asia-Pacific region
  • ARIN: for North America
  • LACNIC: for Latin America and the Caribbean
  • RIPE NCC: for Europe, the Middle East, and parts of Central Asia
  1. Local Internet Registries (LIRs): LIRs are typically Internet Service Providers (ISPs), telecommunication companies, and other large organizations. They get their IP addresses from their respective RIR and then assign them to their customers (both individuals and businesses).

In short, the IANA handles the global allocation of IP addresses, and the RIRs and LIRs distribute them down to the local level.

Types of IP Addresses

The IP Addresses are classified in many ways- Based on Addressing scheme, assignment method and Usage :

  • Based on Addressing Scheme – IPv4 vs. IPv6
  • Based on assignment method – Static vs. Dynamic
  • Based on Usage – Public vs. Private

IP Address v4 Vs IP Address v6

IP Address version 4 (IPv4)

IPv4 is the older version of IP address assigned to the device connected to the network. It is a 32 bit length address written in decimal format with four blocks. Each block is 8 bit in length and is called octate. It is separated by dot (.).

For Examples- 192.168.1.10 – Each block of address ranges from 0 to 255. If each ocatate is breakdown into binary format it contains 8 bits each.

Total number of addresses available in IPv4 is 232 = approx. 4.3 billion addresses. However, IPv4 addresses are rapidly depleted due to enormous growth of Internet users these days. The temporary solution like classless addressing scheme, CIDR, NAT are implemented to control the use of IPV4 address. Still, the demand is very high.

Finally, IPv6 came into existence because the world has run out of IPv4 addresses. The explosion of internet-connected devices, from computers and smartphones to IoT devices, exhausted the limited 32-bit address space of IPv4. IPv6, with its vastly larger 128-bit address space, provides a long-term solution to this problem, ensuring the internet can continue to grow.

IP Address version 6 (IPv6)

An IPv6 (Internet Protocol version 6) address is the next-generation unique identifier assigned to every device connected to a network using the Internet Protocol. It was designed to replace IPv4, primarily to overcome the critical limitation of IPv4: running out of available addresses.

Here’s a breakdown of what an IPv6 address is and why it matters:

  1. The Core Problem IPv6 Solves: Address Exhaustion
    • IPv6 uses 128-bit addresses. This provides a vastly larger address space: 340 undecillion addresses (that’s 340 followed by 36 zeros!). This is enough for every grain of sand on Earth to have its own IP address… many times over.
  2. IPv6 Address Format:
    • Hexadecimal Notation: Written as eight groups of four hexadecimal digits (0-9, A-F).
    • Separated by Colons: Groups are separated by colons (:).
    • Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
    • Compression Rules:
      • Leading zeros within a group can be omitted: 2001:db8:85a3:0:0:8a2e:370:7334
      • One consecutive sequence of groups containing only zero (:0:0:) can be replaced with a double colon (::): 2001:db8:85a3::8a2e:370:7334
      • Important: The double colon (::) can only be used once in an address to avoid ambiguity.
  3. Key Features & Benefits of IPv6:
    • Massive Address Space: Solves the IPv4 exhaustion problem for the foreseeable future.
    • Simplified Network Configuration: Built-in support for stateless address autoconfiguration (SLAAC), allowing devices to configure their own IP addresses without a DHCP server (though DHCPv6 also exists for more control).
    • Efficient Routing: Simplified packet header structure improves router processing efficiency.
    • Improved Security: IPsec (a suite for securing IP communications) was originally designed for IPv6 and is more seamlessly integrated, although it can also be used with IPv4.
    • Better Support for Mobile Devices: Designed with mobility in mind.
    • True End-to-End Connectivity: Eliminates the widespread need for NAT (Network Address Translation), restoring the original design principle of the internet where every device has a unique, globally routable address. This simplifies peer-to-peer applications and services.
  4. Structure of an IPv6 Address:
    • The first 64 bits (/64) typically represent the network prefix (assigned by your ISP or network administrator).
    • The last 64 bits represent the interface identifier, uniquely identifying a specific device on that network segment. This part is often derived from the device’s MAC address (using EUI-64) or generated randomly for privacy (Privacy Extensions).
  5. Adoption Status:
    • IPv6 deployment is steadily growing globally. Most modern operating systems, routers, and network infrastructure support it.
    • Many major websites and ISPs offer IPv6 connectivity.
    • However, IPv4 is still widely used, and the internet largely operates in a dual-stack mode (supporting both IPv4 and IPv6) during the transition period.

In simple terms: An IPv6 address is the much longer, more complex-looking “phone number” of the future internet, assigned to your computer, phone, smart fridge, etc. It exists because we completely ran out of the shorter, simpler “phone numbers” (IPv4 addresses) used in the past. It’s designed to keep the internet growing for decades to come.

Public vs. Private IP Address

A public IP address is a globally unique address that identifies your network to the broader internet. Your ISP assigns this to your router.

  • A public IP address is a globally unique address that identifies your network to the broader internet. Your ISP assigns this to your router. Whereas, A private IP address is used for devices within your local network (like your computer, phone, or smart TV). Your router assigns these addresses to each device, allowing them to communicate with each other on the local network.

Public IP Address

  • Purpose: Globally unique address used to identify your network on the internet. Assigned by your ISP.
  • Scope: Routable over the public internet. Any device can theoretically communicate with it.
  • Uniqueness: Must be globally unique (no two public IPs are the same worldwide).
  • Ownership: Controlled by ISPs and registries (e.g., ARIN, RIPE).
  • Use Case:
    • Your router gets a public IP from your ISP.
    • Servers (websites, email, cloud services) use public IPs.
  • IPv4 Example: 203.0.113.42
    IPv6 Example: 2001:db8:85a3::8a2e:370:7334
  • Security Risk: Directly exposed to the internet → requires firewalls.

Private IP Address

  • Purpose: Used inside a local network (home, office, etc.). Devices behind a router share one public IP.
  • Scope: Not routable on the public internet. Confined to the local network.
  • Uniqueness: Must be unique within the local network, but reusable across different networks (e.g., millions of routers use 192.168.1.1).
  • Ownership: Assigned by a local network administrator or router (via DHCP).
  • Use Case:
    • Devices in your home/office (phones, laptops, printers).
    • Enables NAT (Network Address Translation) to conserve public IPv4 addresses.
  • Reserved Ranges (IPv4):
    • Class A: 10.0.0.0 – 10.255.255.255 (16+ million addresses)
    • Class B: 172.16.0.0 – 172.31.255.255 (1+ million addresses)
    • Class C: 192.168.0.0 – 192.168.255.255 (65k addresses)
  • IPv6 Private Addressing:
    fc00::/7 (Unique Local Addresses – ULAs), e.g., fd12:3456:789a::1.

Static Vs. Dynamic Address

Static IP addresses are manually assigned to a device and remain fixed, never changing unless reconfigured. They’re ideal for servers, printers, or devices requiring permanent accessibility (e.g., hosting a website). 

Dynamic IP addresses, assigned automatically by a DHCP server, are temporary and can change over time (e.g., when a device reboots). This efficient approach is standard for most client devices like laptops and phones, conserving addresses and simplifying network management. While static IPs offer stability, dynamic IPs provide flexibility and scalability.

Conclusion

IP addresses are the foundational identifiers of the internet, enabling devices to communicate across networks. IPv4 (32-bit) paved the way but faced exhaustion, leading to IPv6 (128-bit) for future scalability. Addresses split into public (globally unique, internet-facing) and private (local-network use, conserved via NAT). Assignment can be static (fixed, manual) for critical services or dynamic (temporary, DHCP-managed) for flexibility. Together, these systems sustain connectivity, security, and efficiency across billions of devices — from smartphones to servers — forming the backbone of our digital world.

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