Re: Reverse DNS with Multiple Virtual Hosts

Steve,

Thanks for the response and detailed information, helped a lot.

Derek



"Steve Duff [MVP]" <ergodic@xxxxxxxxxxxxxxxxxxx> wrote in message
news:u2CvnUPjFHA.3300@xxxxxxxxxxxxxxxxxxxxxxx
> While it is possible and not I believe technically invalid to define
> multiple PTR records for a single IP, it can cause problems when used on a
> public DNS, and it would be pointless besides simply because applications
> will only use the first one returned in the response.
>
> Standard mail system reverse DNS checks are happy if they see >any< public
> reverse name for the sender's IP. I've seen a couple that try to skim out
> the "junk" rDNS names assigned by default by larger ISPs. It is also
> possible for the receiver to do a 'round-trip' on the rDNS name to verify
> the original IP matches one in that response, or that there is a matching
> public MX for the domain. All these types of checks should pass for a
> public mail server, and are easy to verify with nslookup or at a testing
> website.
>
> But if the receiving mail server is insisting that the reverse lookup map
> directly to the sender's domain (and isn't doing any alternative checks
> such as SPF, MX, etc.) then it is being way too aggressive. Virtual
> domains on overloaded IPs are quite common and I can pretty much guarantee
> that such a mail server is tagging or dropping a lot of valid mail.
>
> Steve Duff, MCSE, MVP
> Ergodic Systems, Inc.
>
> "Derek" <dg364@xxxxxxxx> wrote in message
> news:OvqfuCOjFHA.2644@xxxxxxxxxxxxxxxxxxxxxxx
>> Hello,
>>
>> I've been racking my brains on this one. I have multiple websites
>> hosted on a DC with integrated DNS (2K3). Everything on the domains
>> works fine, the DNS is set and the websites are all running perfectly.
>> However, when one of them recently sent Email it was rejected due to an
>> inability to perform a reverse lookup on the IP. When doing a reverse on
>> the IP which all of the sites are hosted on only one the domain names
>> comes up. How can I get DNS to respond with all of them to avoid this
>> problem?
>>
>> Thanks,
>> Derek
>>
>>
>>
>
>


.

Relevant Pages

  • Re: Reverse DNS with Multiple Virtual Hosts
    ... Standard mail system reverse DNS checks are happy if they see>any< public reverse name for the sender's IP. ... on the rDNS name to verify the original IP matches one in that response, or that there is a matching public MX for the domain. ...
    (microsoft.public.windows.server.dns)
  • Re: Sendmail config: sending emails with LAN IP vs. domain
    ... > I think you need to do a couple things but w/o seeing your setup it's ... make sure you have reverse entries in your DNS for your mail ... > server so that if a receiving mail server ... > can do a reverse lookup to validate. ...
    (alt.os.linux.suse)
  • Re: Reverse DNS with Multiple Virtual Hosts
    ... You probably just want to configure your mail server to present itself the ... same as your reverse DNS entry, regardless of internal mail domain to/from. ...
    (microsoft.public.windows.server.dns)
  • MX records A records and email
    ... I have a question about dns and email routing. ... provider came back with this response to my inquiry saying the problem lies ... My problem with this response ... resolving the first IP which isn't a mail server." ...
    (microsoft.public.windows.server.dns)
  • Re: MX records A records and email
    ... > I have a question about dns and email routing. ... > The provider came back with this response to my inquiry saying the ... > actually answers as a mail server). ... instead of a host name with an A record. ...
    (microsoft.public.windows.server.dns)