fullfatdesigns

Well-Known Member
Aug 1, 2014
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Hi

I've recently changed my hostname in whm and I need to create a sub-domian that matches. But I get the message;

There was a problem creating the sub-domain:
Sorry you cannot create a subdomain with the same name as the hostname of this machine (xxxxxxx.xxxxxxx.net).

Is there any way around this, as I'm trying to match the domain to the hostname with a rDNS.

Regards
Wayne
 

cPanelLauren

Product Owner
Staff member
Nov 14, 2017
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Hi @fullfatdesigns


You shouldn't be creating a separate subdomain for the hostname, it will cause issues on the system. The rDNS doesn't need to resolve back to the domain name, just the hostname of the server. For each IP address on the server that will be sending mail, I would suggest creating rDNS using the hostname of the server - all it needs to do is resolve the IP to the hostname to be accepted.

Thanks!
 

fullfatdesigns

Well-Known Member
Aug 1, 2014
72
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Root Administrator
Hi Lauren

Thanks for your reply. Originally I had the rDNS on a domain and the hostname was something else, but I was getting an error when testing email in mail-tester.com of;

-1.999 FSL_HELO_BARE_IP_2 IP used in the HELO request
The hostname should be a domain name, not an IP address

So I contacted back my hosting provider and they suggested changing the hostname to match the domain. Is that correct?

Also to point out, the account I setup with the same domain as the hostname was only to create a sub-domain, the account won't be used for anything else.

Regards
Wayne
 

cPanelLauren

Product Owner
Staff member
Nov 14, 2017
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Hi Wayne,

-1.999 FSL_HELO_BARE_IP_2 IP used in the HELO request
The hostname should be a domain name, not an IP address
That specific error is because you had the rDNS set up to resolve the IP to a domain name or you had an IP set in the mailhelo. Have you made modifications to /etc/mailhelo? This should resolve the IP to the hostname of the server and does not require a separate subdomain to be created, as long as the hostname has an A record that resolves it to the server the Reverse DNS will resolve the IP back to the hostname. The hostname of the server should not be modified to a domain name.

So I contacted back my hosting provider and they suggested changing the hostname to match the domain. Is that correct?
No that is not correct, you should not change the hostname to match the domain.


I think that the issue here may be a misinterpretation of the error. When you run the following can you show me what you get (removing any identifying information of course)

Code:
host <ipaddresshere>
Can you also let me know if you have anything in /etc/mailhelo
 

fullfatdesigns

Well-Known Member
Aug 1, 2014
72
11
8
cPanel Access Level
Root Administrator
Hi Lauren

I've changed my hostname so its not the same as the rDNS. I've gone to create the sub-domain for the rDNS (as it currently doesn't exist) and I'm getting this message;

There was a problem creating the sub-domain:
(XID zeqkf7) A DNS entry for the domain “xxxxx.xxxxxxxxxx.net” already exists.

I'm not sure what to do next?

Regards
Wayne
 

cPanelLauren

Product Owner
Staff member
Nov 14, 2017
13,296
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Houston
Hi Wayne,


That error indicates that there's a DNS entry for the domain already present, you'd need to check the existing DNS records first. Ultimately though, it sounds like rDNS needs to be updated to match the hostname of the server.

Thanks!
 

fullfatdesigns

Well-Known Member
Aug 1, 2014
72
11
8
cPanel Access Level
Root Administrator
Hi Lauren

I'm confused, I thought that I didn't want the rDNS to match the hostname of the server? I can't set the hostname to be the same domain as the hostname because I can't create the sub-domain...

Regards
Wayne
 

cPanelLauren

Product Owner
Staff member
Nov 14, 2017
13,296
1,271
313
Houston
Hi Wayne,


The rDNS should resolve the IP address of the server to the hostname, always. It shouldn't resolve to another domain or an IP address. You should not need to set the hostname to be the same domain as the hostname.

For example:

My Hostname:
server.example.com

resolves to the IP address:
1.2.3.4


I would then create rDNS that resolved my IP to server.example.com:

Code:
4.3.2.1.in-addr.arpa     IN      PTR      server.example.com     14400s

My domains example.com and domain.com both resolve to the IP address 1.2.3.4 and both would work without issue using the PTR record as described here without any other modifications in place.


I hope this helps.

Thanks!