[TheLoneAdmin]

The list lists four different ways: dotted, decimal, hex and octal. The other 117 entries are just combinations of the four.

[aboutruby]

Also I didn't know you could group sub-groups, e.g. http://209.0xd8.59120, http://209.0xd8e6f0 and http://0xd1d8e6f0

[lucb1e]

I personally found it surprising that the formats can be mixed arbitrarily within dotted notation.