Simple rDNS question

[rvnet]

Hi,

rDNS should point to web site name. Right?
Ex: my ip 11.22.33.44 should point to mysite.com

When I asked my host (myhost.com) to set up rDNS to ONE OF my sites (I have a VPS on which my sites are hosted), they set it up for me. So when I enter my ip at rDNS tool, I am getting this:
11.22.33.44-static.mainhost.com

(myhost.com is reseller of mainhost.com)

Is this correct? They said it is OK.

thanks much.

 

[tillo]

There are no strict rules.
Usually if you have 1 IP address it should point (because of SMTP's RFC) to your server's FQDN: its complete hostname, like something.yourdomain.example.

But it may point to anything, and if your contract doesn't explicit say that you can choose your rDNS the hoster have the right to set the hostname to "11.22.33.44-static.mainhost.com" or to any other value.
The important thing is that this hostname should resolve back to the IP address.
I could have checked this for you, if you didn't obfuscate your DNS data.

You should also notify your hoster that the canonical way to set up an automatic rDNS is by translating 11.22.33.44 to 44-33-22-11.something.hoster.example otherwise some broken services could get confused and take the host as an IP... but this is something many ISP do wrong and probably always will.

 

[nobaloney]

tillo,

We do a lot of DNS and a lot of rDNS (multiple servers worldwide). The biggest problem we have is when the upstream host delegating authority to us for rDNS for the IP block doesn't use a standard zone name. So when rDNS doesn't work and the upstream assures us we've been delegated as authoritative, we do a dig +trace to see the immediate upstream's zone name, and make sure we use the same. For example, for 192.168.33.0/24:

$ dig -x 192.168.33.0 +trace

Also, note if the canonical method you point out is used many large ISPs and mail services will not accept email from you; they'll (wrongly) presume you're using an ISP's dynamic IP block. Best to always use the hostname if a shared IP#, and the domain name (without the www if a dedicated IP#. That's always worked well for us.

As you point out, most important for mail delivery that whatever rDNS points to, points back to that IP#.

Jeff

 

[rvnet]

Thanks both of you! It seems host has fixed the issue. Now rDNS displaying my site name.