ISPs usually use the designated block (100.64.0.0/10) for this to avoid collisions with home networks: https://tools.ietf.org/html/rfc6598#section-7 https://too

ISPs usually use the designated block (100.64.0.0/10) for this to avoid collisions with home networks: https://tools.ietf.org/html/rfc6598#section-7 https://tools.ietf.org/html/rfc6598#section-7 Webpass is an example of a "good" ISP that does this. It's my only qualm with them. Besides that they are outstanding. IPv6 works great.