Facebook’s custom IPv6 range
I noticed an interesting thing with a certain visitor after posting a blog post to Facebook. The IP address that the Facebook crawler uses to visit the site on callback to get meta-data has a custom IPv6 sub-range. IPv6: 2a03:2880:ff:1a::face:b00c Host: fwdproxy-prn-026.fbsv.net Notice 2a03:2880:ff:1a::<strong>face:b00c</strong> How this is done The IPv4 addresses could only use regular integers (decimal); numbers between 0 and 9. However, IPv6 can use any and all hexadecimal; 0-9 and a-f....