It's not weird. Many ISPs have dynamic prefixes, and even with "just" 56 bits that prefix is long and not very memorable. Thus ULA is a must on the inside, and

It's not weird. Many ISPs have dynamic prefixes, and even with "just" 56 bits that prefix is long and not very memorable. Thus ULA is a must on the inside, and DynDNS is still required for anything internet facing.