Two points: There's nothing wrong with using the CNAME if you're only serving comments off that domain. Also, I'm pretty sure you can regex adblocking DNS ent

Two points: There's nothing wrong with using the CNAME if you're only serving comments off that domain. Also, I'm pretty sure you can regex adblocking DNS entries, so you could block on comments.. pretty easily with minimal casualties. You'd have to intentionally randomize it to bypass adblockers... Which will probably get your domain listed as a badhost by most peers. (Smarter adblockers would check for CNAMEs and IP blocks, but let's not ecalate the arms race for no reason.)