Just set an A record to foo.net The way I do it is probably incorrect (nslint complains) but I set an A record to foo.net and to www.foo.net, then set everything else up as cnames. foo.net. IN A 1.2.3.4 www.foo.net. IN A 1.2.3.4 ftp.foo.net. IN CNAME www.foo.net. mail.foo.net. IN CNAME www.foo.net.
I had to do something similar for my nameserver, which is foo.com. My registrar wouldn't let me register a nameserver that was the same as the domain name, so I ended up creating a second A record for ns1.foo.com. I understand that in theory you're not supposed to have two A records pointing to the same IP address, but it seems to be sometimes unavoidable.
John