IP (Version 4) Address Format Validator

If you are a software developer or tester of communication applications, you need to know what is a valid IP addresses and what is an invalid IP address. This page allows you to learn and test valid version 4 IP addresses.

What is a valid IP address?

An IP address is an identification assigned to a computer host on the Internet. The current version of IP address (version 4, IPv4) uses 32 bits or 4 bytes to represent IP addresses. This format gives 4,294,967,296, about 4,294 million, possible unique IP addresses.

A 4-byte IP address is normally represented with 4 decimal numbers separated by dots (.). For example, is a version 4 IP address. Validation of this IP address format is very simple.

But not all IP addresses are used to assigned to computer hots on the Internet. A lots of them are reserved for special uses only. Here are some examples of reserved IP address ranges:

  • - Reserved for loopback and private network use only.
  • - Reserved for private network use only.
  • - Reserved for private network use only.
  • - Reserved for IPv6 to IPv4 relay use only.

How to valid IP addresses?

In order to help your programming or testing tasks, FYIcenter.com has designed this online testing page for you to validate any given IP address, using two techniques below:

  • Using regular expression /(^127)|(^192)|(^10)\./ to exclude reserved IP addresses.
  • Using ip2long($ip) function to validate IP address format.

All you need to do is to enter an IP address in the form below and click the Start button.

IP Address:

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