Those representations for 127.0.0.1 work too, just try to ping them: 0177.1 (octal, 2 stripped 0s, decimal one) 017700000001 (octal) 2130706433 (decimal)

Those representations for 127.0.0.1 work too, just try to ping them: 0177.1 (octal, 2 stripped 0s, decimal one) 017700000001 (octal) 2130706433 (decimal) 127.0.0x1 0x7f.0x0.0x0.0x1 127.000.000.001