Nicholas
asked on
rDNS on single IP and multiple domains
Just moved to a new server and this is the one thing that I always forget about.
I have 2 IP's with multiple domains hosted on them.
How do I set it up so that rDNS works ok for all sites?
I'm fairly au fait with Linux but not DNS, the one thing that always confuses the hell out of me.
I understand each IP can only have one rDNS record which will work fine for the primary domain but how do I set up the other domains using the same IP so they are not rejected as spam?
Do I set the MX record to the primary domain for each domain?
Do I need to add something to the SPF record?
I'm sure it's a fairly simple solution
Thanks
I have 2 IP's with multiple domains hosted on them.
How do I set it up so that rDNS works ok for all sites?
I'm fairly au fait with Linux but not DNS, the one thing that always confuses the hell out of me.
I understand each IP can only have one rDNS record which will work fine for the primary domain but how do I set up the other domains using the same IP so they are not rejected as spam?
Do I set the MX record to the primary domain for each domain?
Do I need to add something to the SPF record?
I'm sure it's a fairly simple solution
Thanks
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You can't have an rDNS record for multiple Domains, but neither do you need to.
You just need 1 rDNS record and, as long as it resolves to something, that's good enough.
If your primary Domain is abc.com and another Domain is xyz.com, point your rDNS at 'mailserver.abc.com'.
Within your public DNS for abc.com, create an SPF record with, at minimum 'v=spf1 mx -all'
This means that abc.com is allowed to send mail on behalf of any Domains 'mailserver.abc.com' receives mail for, based on any MX records that point at that public IP address (such as xyz.com).
You just need 1 rDNS record and, as long as it resolves to something, that's good enough.
If your primary Domain is abc.com and another Domain is xyz.com, point your rDNS at 'mailserver.abc.com'.
Within your public DNS for abc.com, create an SPF record with, at minimum 'v=spf1 mx -all'
This means that abc.com is allowed to send mail on behalf of any Domains 'mailserver.abc.com' receives mail for, based on any MX records that point at that public IP address (such as xyz.com).
Don't just randomly do that. The SPF record indicates where any one sending has abc.com has to relay through and that might not be correct.
If your server name is mail.example.com, set up forward and inverse DNS to match that and you're done.
If your server name is mail.example.com, set up forward and inverse DNS to match that and you're done.
Jan, what do you mean by 'inverse DNS'?
inverse = reverse = rDNS (what we used to call it years ago)
ASKER
I have a txt record for domain1.com set as "v=spf1 mx a ~all"
An A record for mail pointing to the IP and an MX record pointing to mail.domain1.com
On domain 2 I have an A record for mail pointing to the same IP and an MX record pointing to mail.domain2.com
The server's hostname is domain1.com and the rDNS is set to this and a reverse IP lookup returns this
Checking both domains I still get an error on Reverse DNS is not a valid Hostname
So where am I going wrong?
An A record for mail pointing to the IP and an MX record pointing to mail.domain1.com
On domain 2 I have an A record for mail pointing to the same IP and an MX record pointing to mail.domain2.com
The server's hostname is domain1.com and the rDNS is set to this and a reverse IP lookup returns this
Checking both domains I still get an error on Reverse DNS is not a valid Hostname
So where am I going wrong?
Have a look at mail-tester.com. Run a test from both domains and post the results (feel free to sanitise them).
ASKER
Cannot even send an email at the moment as I'm getting Temporary lookup failure
Show us a real fully qualified domain name and we can tell you within minutes.
ASKER
Reinstalled server and all working fine now
ASKER
The server has the main domain configured and setup, the only current issue is "Reverse DNS is not a valid Hostname"