My advice was selfish. I run a personal server that is IPv6 connected, and sometimes web frameworks will break because the author tried to store e.g. REMOTE_ADD

My advice was selfish. I run a personal server that is IPv6 connected, and sometimes web frameworks will break because the author tried to store e.g. REMOTE_ADDR in a VARCHAR(16) column. So I would like to promote the fact that IP address != 32 bits, and if you really want to optimize for IPv4 address lookup, your code needs to handle it as a separate, specialized case.