Stan Hoeppner a écrit : > [snip] > A web server with a single IP address hosting 378 vitural domains. Should > it have 379 PTRs? One for the host itself and one for each virtual domain? > Of course not. > > A mail server with a single IP address hosting 378 mail domains? Should it > have 379 PTRs? One for the host itself and one for each virtual MX domain? > Of course not. In this case, the DNS infrastructure isn't smart enough to > return matching records even though they do exist, so why bother?
Stan, you're confused. What is "asked" for is: - if an IP is used to send mail, then it should have at least one PTR (preferably only one) - _any_ PTR returned for this IP should resolve back to the IP (the _nay_ is because no server is going to spend hours trying to resolve 3000 PTRs...). This has nothing to do with virtual hosts and the like. As you can guess, imlil.netoyen.net is hosting many domains. but the IP has only one PTR and that PTR resolves back to that IP. (and the box has multiple IPs too, which correspond to various hostnames...). When you run a "server" (something that listens to requests), you don't care about reverse DNS. so www.example.com only needs to resolve (that's what the browser does). nobody is going to resolve the IP back to a name (that would be stupid). When you run a "client" (something that initiates a TCP connection...), you'd better have "FCrDNS" (IP -> name ->IP returns original IP). well, all this may go away with IPv6. but as of IPv4, it is common practice... (I don't know if this is still the case, but gandi.net won't allow you to query their whois if you have that "wrong"). > [snip]
