At 19:47 1/12/2004, Jeffrey Laramie wrote: >In a standard DNS configuration you would have a domain 'zone' file for >each domain name and a 'reverse lookup' zone file for each block of IPs. >The zone file typically has records that resolve a name to an IP address: > >myhost A 12.34.56.78 > >The reverse lookup zone file has the opposite record: > >78 PTR myhost.mydomain.org > >The reverse lookup zone file knows what domain each IP is in. If a >remote mail server does a reverse lookup and gets mydomain instead of >myseconddomain, then it's configured wrong and you need to contact the >ISP or whomever handles DNS for these domains. It would be good policy >for the remote mail server to reject any address that fails RDNS lookup >since it's most likely either spoofed or broken. There are cases where there is overlap between multiple domains and the same IP space (web hosting comes most prominently to mind, but there are other situations).
For instance, if you look up the following DNS names: mail.vbot.org mail.arisiasoft.com You will find they both resolve as 66.219.172.36 - if you look up 66.219.172.36, it should resolve as: karen.arisiasoft.com You'll note that neither of the mail names match the PTR record (one matches at the primary domain level, but not a complete match). Both of the mail. DNS names point to the same machine - mail for both domains is hosted there (on the same copy of Xmail). >If a >remote mail server does a reverse lookup and gets mydomain instead of >myseconddomain, then it's configured wrong and you need to contact the >ISP or whomever handles DNS for these domains. If I understand your logic here, you are saying that because mail.vbot.org --> 66.219.172.36 --> karen.arisiasoft.com, you would recommend rejecting all mail from mail.vbot.org? Even though it has a valid RDNS (even if it doesn't match the original DNS name), and a valid MX record for the domain pointing to the same IP address? I think if you followed through on that, you would end up rejecting a lot of mail from a lot of places... - To unsubscribe from this list: send the line "unsubscribe xmail" in the body of a message to [EMAIL PROTECTED] For general help: send the line "help" in the body of a message to [EMAIL PROTECTED]
