No reverse DNS (PTR) entries

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Posted by bary40, 05-01-2012, 07:20 AM
Hello, I have a dedicated server. I set up my DNS records. Everything works fine, except one thing When i do a DNS test for my domain i get this error ERROR: No reverse DNS (PTR) entries. You should contact your ISP and ask him to add a PTR record for your ips This error is related to my mail server's IP I contacted them and they told me that they added a PTR record, but the error still exist, I contacted them and the last response was: We did a trace route to mail.mydomain.co.uk fails at your server 1 <1 ms <1 ms <1 ms xxx.xxx.xxx.xxx 2 1 ms 1 ms 1 ms vl555-gw.hex.as29550.net [213.229.80.67] 3 23 ms 15 ms 10 ms a.6.magic-hex.as29550.net [213.229.122.210] 4 * * * Request timed out. 5 * * * Request timed out. Hop 4 should be a response from your server but your server is not responding on the IP or announcing a service on this IP. You will need to correct the configuration error on your server. How to test if there is a problem with my configuration. Any idea on how to resolve this error will be appreciated. Thank you
Posted by hoststopuk, 05-01-2012, 07:41 AM
Try accessing PTR test. Enter the IP and select A record from the dropdown. Click on Resolve. See, what output you get. This might help to troubleshoot.
Posted by bary40, 05-01-2012, 07:48 AM
I did the test and the result was Nameserver ns6.eukhost.com. reports: No such host xxx.xxx.xxx.xxx.in-addr.arpa. what does it meam? there is no rDNS record for my IP? But the company told me that they add a rDNS record for my IP and i can see that on there portal. Any Idea?
Posted by InfiniteTech, 05-01-2012, 07:52 AM
Two separate issues: 1- PTR entries are not instantly available. For simplicity, they can be added only by your ISP. Its just another DNS record and the same rules apply. It would take some time to propagate. 2- I think traceroute uses ICMP. So you might need to allow ICMP protocol response in your firewall. If you have iptables, use this: The above rules should be at the very top of your rules list. Last edited by InfiniteTech; 05-01-2012 at 07:58 AM.
Posted by RDSNetworking, 05-01-2012, 07:56 AM
Have you added the PTR record to your zone files?
Posted by bary40, 05-01-2012, 08:10 AM
I've created a reverse lookup zone, added a record for my IP and when i did a trace route to my mail server, everything goes well with no erros. When i do a DNS test for my domain i get the same error, does it require some time to propagate and fix this error?
Posted by InfiniteTech, 05-01-2012, 08:12 AM
You can't do it yourself. You need your ISP (host) to do it for you since the IP has nameserver delegation set to their servers (usually) at ARIN/RIPE end. Unless your host/ISP confirms that the IP range has been delegated to your nameservers, you doing anything with the reverse zone will not work.
Posted by bary40, 05-01-2012, 08:23 AM
But how do you explain that when doing a trace route for mail server without creating the reverse lookup zone and adding the appropriate record fails, and when i created it did not fail? My ISP told me that they have add a PTR record for my IP.
Posted by InfiniteTech, 05-01-2012, 08:29 AM
PTR records and traceroute have nothing to do with each other. They were merely co-incidences for you. For your trace route problem, please refer to my previous post regarding ICMP response and firewall.
Posted by bary40, 05-01-2012, 08:37 AM
Thank you for you answers, but i think iptables is for Linux, is it right? I have windows on my server, is there is something similar for windows?
Posted by bary40, 05-02-2012, 03:54 AM
OK, in Windows if ping is enabled, the trace route for mail server successes but how can i check the source of the following error ERROR: No reverse DNS (PTR) entries. You should contact your ISP and ask him to add a PTR record for your ips Ho to determine what is the cause of this error, is it because that my ISP did not add a PTR record for my IP, or it could be an error in the configurations on the server? The ISP told me that he added a PTR record.
Posted by pititis, 05-02-2012, 08:39 PM
Easy. Check what they did. you can use the linux command host or try an online test. The result must point to your host i.e server.domain.com did you ask for an explicit entry like this? Last edited by pititis; 05-02-2012 at 08:45 PM.
Posted by bary40, 05-02-2012, 10:36 PM
I have Windows server, not Linux.
Posted by pititis, 05-03-2012, 06:20 AM
Please don't stop where the word "linux" is...
Posted by bary40, 05-03-2012, 06:31 AM
OK, using the online test gives no results for reverse record for the IP, I told the ISP about this, and they told me that maybe the database where i did the test is not up to date and it may require some time to be updated, because of that i asked and still asking if there is a way to do a test locally from the server if the IP has a reverse record.
Posted by pititis, 05-03-2012, 06:48 AM
Locally? Sure, in windows use: nslookup ipaddress
Posted by foobic, 05-03-2012, 06:56 AM
There's nothing special about testing from the server - the rDNS records aren't there. If you can find a machine with dig installed on it (that's most likely a *nix system, but you could probably find a version of dig for Windows somewhere) then you could use this: (replace "4.3.2.1" with your IP address, reversed, ie. if your IP was 1.2.3.4 you'd use the command as above). But wouldn't that risk getting a cached (non) result from his ISP's resolver?
Posted by bary40, 05-03-2012, 07:07 AM
Yes, i used nslookup but it returns Non-existent domain.
Posted by bary40, 05-03-2012, 07:09 AM
Thanks, I'll search for a version of dig for Windows.
Posted by foobic, 05-03-2012, 07:22 AM
This looks promising (check the last comment).
Posted by bary40, 05-03-2012, 07:58 AM
OK, I'll check it. Thank you.