chris0147

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Aug 28, 2015
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Hi all,

I need some help with Reverse DNS as I have got a problem with it. I have setup rDNS on my hosting provider which I use rdns1.mydomain.com and I have a server hostname which it is gateway1.mydomain.com. I want to use both different name because of the email providers that want to see both different names so my email would go to inbox.

When I open on the Email Deliverability software through in the cpanel, I can see this:

- Removed -



Can you please advice me with what I need to do?

How I can match with the rDNS?

Do I need to change the server hostname to match with the rDNS or what?

I want to use smtp513.mydomain.com to send the email and I want to use gateway1.mydomain.com to get access to whm and cpanel. I am not sure what I need to do so I need your help with this.

Any advice would be much appreciated.

Thanks in advance.
 
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keat63

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I don't know enough about this to offer anything concrete, but when I set my server up, I had to contact my data centre and ask them to configure RDNS at thier end.
This was nothing that I had any control over.
 

chris0147

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Aug 28, 2015
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Oh right, well I want to use two different IPs to point it in PTR in a single hostname but I cant now because the PTR will only allow you to setup with one IP in a single hostname. I want to setup two different smtp addresses that come with two different IPs, e.g: 106.x.xx.59 and 106.xxx.xxx.202 as the 106.x.xx.59 will be using for smtp513 and 106.xxx.xxx.202 will be using for smtp516 as a backup. The other way I could do is buy another VPS to transfer the IP and point it to PTR that match with the hostname. I am sure someone on here might know better than I do?
 

uk01

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Dec 31, 2009
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**removed**

turned out to be a sporadic issue with a second ip on one server
 
Last edited:

cPanelLauren

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uk01

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Dec 31, 2009
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Hello,

The documentation here should be useful: How to Configure Reverse DNS for BIND in WHM - cPanel Knowledge Base - cPanel Documentation

I do also want to point out that the rDNS should resolve back to the hostname of the server not a domain name.
However, we did find an issue with a reseller account. It was flagging an error on their deliverability as they send email from the second ip on the server.
They don't pay for a dedicated ip, but they are the only ones using it, so for now I changed the RDNS at our datacentre to their main domain.
Interestingly this corrected the issue for all their domains.

I'm not sure what a host would do if the reseller was sharing the ip address.
 

chris0147

Well-Known Member
Aug 28, 2015
104
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68
London
cPanel Access Level
Root Administrator
Hello,

The documentation here should be useful: How to Configure Reverse DNS for BIND in WHM - cPanel Knowledge Base - cPanel Documentation

I do also want to point out that the rDNS should resolve back to the hostname of the server not a domain name.
@cPanelLauren, thank you for your advice. I have already added Rerverse DNS on my server as I have followed the tutorial on youtube the same as what you sent me the link.

Here is what it show:

dig +nssearch 101.189.106.in-addr.arpa.

[[email protected] ~]# dig +nssearch 101.189.106.in-addr.arpa.
SOA rdns1.example.com. support.domain.us. 2015010535 28800 7200 604800 86400 from server 104.128.xxx.8 in 0 ms.
SOA rdns1.example.com. support.domain.us. 2015010535 28800 7200 604800 86400 from server 104.128.xxx.3 in 25 ms.



When I try this:

host 106.189.xxx.59

[[email protected] ~]# host 106.189.xxx.59
Host 59.xxx.189.106.in-addr.arpa. not found: 3(NXDOMAIN)



Do you know what I need to do?

On my DNS, it show like this 59.101.xxx.106.in-addr.arpa. so do I need to add the 59 before the 101 or what?

The hostname of the server is server.mydomain.com so the rDNS have resolve to smtp513.mydomain.com, is that wrong?
 
Last edited:

cPanelLauren

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Hi @chris0147


First, are you sure that your provider delegates access to update rDNS to you? It may be that you're not able to add it. Based on this output it looks like it's not coming up - a PTR record is always going to list the IP address backwards.
 

chris0147

Well-Known Member
Aug 28, 2015
104
2
68
London
cPanel Access Level
Root Administrator
Hi @chris0147

First, are you sure that your provider delegates access to update rDNS to you? It may be that you're not able to add it. Based on this output it looks like it's not coming up - a PTR record is always going to list the IP address backwards.
@cPanelLauren:

Well I am not be able to add the hostname in the rDNS record, because the hostname have a different IP so what I can do?

Do I need to change the IP in the DNS so I can add it in the rDNS record on my hosting provider?

If I want to use smtp516.mydomain.com, do I have to get another server to add gateway2.mydomain.com in the rDNS record as the gateway1.mydomain.com is already exist in the rDNS record?
 
Last edited:

uk01

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Dec 31, 2009
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Hi @uk01

What was the PTR set to on the secondary IP address? It should function the same.
Hi the reseller used to use the secondary ip but now uses the primary as we had to switch mainip due to a Cpanel license issue after uninstalling Cloudlinux.

Now
Cpanel/main ip > ip 1
Reseller > all domains are ip 1
Other accounts > ip 2

hostname.ourdomain.com > ip 2
RDNS for ip 2 > hostname.ourdomain.com
RDNS for ip 1 > resellerdomain.com

If the RDNS for ip 1 is not the reseller domain we get this message:

The system sends “resellerdomain.com”’s outgoing email from the “**ip 1**” IP address. The only PTR value for this IP address must be “resellerdomain.com”. This is the name that this server sends with SMTP’s “HELO” command to send “resellerdomain.com”’s outgoing email.

1 unexpected PTR value exists for this IP address:
  • hostname.ourdomain.com
If we change the hostname to ip 1, same as Cpanel, we get issues with the other domains HELO.
Setting the reseller as the RDNS for their ip resolves the issue as luckily we do not share that ip.
 

cPanelLauren

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Hi @uk01


The reseller IP needs to have an A record for the hostname as well. In that instance, the PTR should function without issue. Right now my assumption is the only A record associated with it is the reseller's domain.
 

uk01

Well-Known Member
Dec 31, 2009
204
19
68
Hi @uk01


The reseller IP needs to have an A record for the hostname as well. In that instance, the PTR should function without issue. Right now my assumption is the only A record associated with it is the reseller's domain.
so 2 records pointing to the same ip?
  • hostname.ourdomain.com >>> to ip 1
  • hostname.ourdomain.com >>> to ip 2
I didn't think we should point the same sub domain to 2 ip's
 

cPanelLauren

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All an A record does is map a domain name to an IP address. You can use multiple A records for the same domain, in this instance the hostname. You'd either need to do that to resolve the PTR properly or again, you'd need to use a domain whose A record is already mapped to that IP address.

This will not affect domain's that have the same IP address assigned as the Apache VirtualHost manages to the per domain configuration.


Thanks!
 

uk01

Well-Known Member
Dec 31, 2009
204
19
68
All an A record does is map a domain name to an IP address. You can use multiple A records for the same domain, in this instance the hostname. You'd either need to do that to resolve the PTR properly or again, you'd need to use a domain whose A record is already mapped to that IP address.

This will not affect domain's that have the same IP address assigned as the Apache VirtualHost manages to the per domain configuration.


Thanks!
@cPanelLauren thanks for that info, that's great.
That's why the reseller.com domain works on the RDNS then as that domain points to the the ip. I realise now if I have the hostname pointing to the second ip too, then the hostname will work ok for the RDNS.
Cheers
 
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