Hmmm, I think it might have problems with underscores in hostnames. Before you say that underscores aren't valid, they very much are. They're used for DKIM and

Hmmm, I think it might have problems with underscores in hostnames. Before you say that underscores aren't valid, they very much are. They're used for DKIM and SIP for example: root@haven:~# host -t txt dkim1._domainkey.grepular.com dkim1._domainkey.grepular.com TXT "k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDwe0CGlJQq6Y0poniuhn80rsC1kKrcVg19STXqgM8wxe4HidRjr8KfSfCo0wcgqVq8saqsB0JCt2WOquRlUG5qRtrZag6G/wpYkRYCjYm8VsaJDxNZFpiauXeyz9HGKkHTo2QxLVIYFzkSo7ZtRQNnUB1N12/v5BscLk6X1DlmawIDAQAB" root@haven:~# host -t srv _sip._tcp.grepular.com _sip._tcp.grepular.com SRV 10 0 5060 voip.grepular.com root@haven:~# Not just underscores. You can shove almost anything in the hostname part of a dns lookup...