IP Address Validator

Validate IPv4 and IPv6 addresses instantly. Check if an address is valid, determine its type, class, and whether it's public or private.

Test examples:

What is IP Address Validation?

IP address validation checks whether a given string is a properly formatted IPv4 or IPv6 address. This includes verifying that the address follows the correct syntax, uses valid number ranges, and conforms to the standards defined in RFC 791 (IPv4) or RFC 4291 (IPv6).

Beyond simple format checking, our validator also identifies the address type (public, private, loopback, etc.), determines the IP class for IPv4, and provides additional details about the address's purpose and routability. For subnet calculations with validated addresses, use our subnet calculator.

Validation Rules

IPv4: Four decimal numbers (0-255) separated by dots. Leading zeros are allowed but discouraged.
IPv6: Eight groups of 4 hex digits separated by colons. Consecutive zero groups can be compressed with ::.

IPv4 Address Types

Public Addresses

Public IP addresses are globally routable on the internet. They're assigned by IANA through regional registries and ISPs. Examples include 8.8.8.8 (Google DNS) and 1.1.1.1 (Cloudflare DNS).

Private Addresses (RFC 1918)

Reserved for internal networks, these addresses are not routed on the public internet:

  • 10.0.0.0/8 - 10.0.0.0 to 10.255.255.255 (16 million addresses)
  • 172.16.0.0/12 - 172.16.0.0 to 172.31.255.255 (1 million addresses)
  • 192.168.0.0/16 - 192.168.0.0 to 192.168.255.255 (65,536 addresses)

Loopback (127.0.0.0/8)

The loopback range (most commonly 127.0.0.1) is used for a device to communicate with itself. Packets sent to loopback addresses never leave the host.

Link-Local (169.254.0.0/16)

Automatically assigned when DHCP fails (APIPA). These addresses are only valid on the local network segment and are not routed.

Multicast (224.0.0.0/4)

Used to send data to multiple recipients simultaneously. Ranges from 224.0.0.0 to 239.255.255.255.

IPv4 Classes

Class Range First Bits Default Mask Purpose
A1.0.0.0 - 126.255.255.2550/8Large networks
B128.0.0.0 - 191.255.255.25510/16Medium networks
C192.0.0.0 - 223.255.255.255110/24Small networks
D224.0.0.0 - 239.255.255.2551110N/AMulticast
E240.0.0.0 - 255.255.255.2551111N/AReserved/Experimental

IPv6 Address Types

  • Global Unicast (2000::/3) - Publicly routable addresses
  • Link-Local (fe80::/10) - Auto-configured, local segment only
  • Unique Local (fc00::/7) - Private addresses (like RFC 1918)
  • Multicast (ff00::/8) - One-to-many communication
  • Loopback (::1) - Device self-communication

For detailed IPv6 subnet calculations, use our IPv6 subnet calculator.

Common Validation Errors

  • Octet out of range: IPv4 octets must be 0-255. "256.1.1.1" is invalid.
  • Wrong number of octets: IPv4 needs exactly 4. "192.168.1" is invalid.
  • Invalid characters: Only digits and dots for IPv4, hex and colons for IPv6.
  • Multiple :: in IPv6: The compression shorthand can only appear once.
  • Too many IPv6 groups: Maximum 8 groups when fully expanded.

For more IP-related tools, explore our CIDR calculator, network address calculator, and IP binary converter.

Special Addresses
0.0.0.0Default/Any
127.0.0.1Localhost
255.255.255.255Broadcast
::IPv6 Unspecified
::1IPv6 Loopback

Frequently Asked Questions

Yes, 0.0.0.0 is syntactically valid but has special meaning. It typically represents "any address" or "all interfaces" when used as a listening address. It can also indicate an unknown or unspecified source. It's not assignable to a host as a regular IP address.

The 192.168.0.0/16 range is designated as private by RFC 1918. Internet routers are configured to drop packets with these source or destination addresses. This allows the same private addresses to be reused in different networks without conflict, with NAT translating them to public addresses for internet communication.

IPv4 validation checks for four decimal octets (0-255) separated by dots. IPv6 validation is more complex: it must handle 8 groups of 4 hex digits, the :: compression notation, and mixed formats like ::ffff:192.168.1.1. IPv6 also allows leading zeros to be omitted within groups.

Related Network Tools

Looking to calculate subnets for your network? You can also view IPs in binary representation. For detailed analysis, determine network boundaries. Network administrators often need to calculate the last address in networks. Additionally, work with IPv6 address allocation. Many users find it helpful to switch netmask to prefix notation. For comprehensive planning, determine appropriate subnet masks.