Question

I need to validate an IP range that is in format 000000000 to 255255255 without any delimiters between the 3 groups of numbers. Each of the three groups that the final IP consists of should be 000 (yes, 0 padded) to 255.

As this is my 1st stackoverflow entry, please be lenient if I did not follow etiquette correctly.

Answer 1

^([01]\d{2}|2[0-4]\d|25[0-5]){3}$ 

Which breaks down in the following parts:

1. 000-199
2. 200-249
3. 250-255

If you decide you want 4 octets instead of 3, just change the last {3} to {4}. Also, you should be aware of IPv6 too.