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Old 11-17-2007, 02:00 AM   #1
Registered: Mar 2007
Posts: 47

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PTR problem

Dear Sir
I am From an ISP company
i need Yours Help Regarding our Reverse Zone Entry Problem . Our IP Address/ DNS Detail is

Primary DNS
Secondry DNS

Mai Server IP :
In Our Local DNS server Their is Reverse Zone Created for each ip range and we can resolve ip to name. as the output of

nslookup is


but While Sending mail to AOL , Indiatimes Etc . 452 sorry no PTR record found for your MTA Comes

So pls tell me if it is need to configure on root server or the problem is on our end .

Last edited by csdhiman; 11-17-2007 at 02:02 AM.
Old 11-17-2007, 07:31 PM   #2
Registered: Nov 2006
Location: Seattle, WA
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From here, it appears the problem is a configuration problem at your end. As you said, the name does resolve to the address However, your MX record for does not give that name. Instead, it
contains the name

Further, the address does not return a name through the standard DNS resolution process, at least from the western US. If I ask your name server directly for the inverse mapping, it does return a name, but it is not the name of your mail server. Instead, it says

So it appears that there is more than one problem here. First, your MX record should include a name that corresponds to its IP address (via an A record, not a CNAME). And second, there is some higher-level difficulty in the DNS system; either your domain is not properly registered with the appropriate root server (I am sorry to say that I do not know how that is handled in India), or there is some intermediate router that is blocking the resolution. I am sorry to report that this is becoming too common as various governments try to control who sees what over the Internet.
Old 11-18-2007, 01:20 PM   #3
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This is a simple problem, but it is beyond your ability to fix. There is a major difference between having a public address or addresses to use, and being authoritative for that address space. Your ISP is most likely authoritative for the IP space, and as a result, only they can create the PTR for your address.

First, nslookup isn't a great tool for DNS troubleshooting, as it doesn't have enough info in default mode. You'll want to get familiar with the tool dig if you're going to work on DNS issues. Here are some good searches that told me you aren't authoritative for that address space -

jim@jimsworktop:~$ dig

; <<>> DiG 9.4.1-P1 <<>>
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49417
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;                IN      A

;; ANSWER SECTION: 86400   IN      A

;; AUTHORITY SECTION:          86400   IN      NS          86400   IN      NS

;; ADDITIONAL SECTION:        86399   IN      A       86399   IN      A

;; Query time: 796 msec
;; WHEN: Sun Nov 18 14:02:28 2007
;; MSG SIZE  rcvd: 135
Ok, that confirms that you do have your mail server at the address you said, but I also see that you aren't doing your own DNS. The ISP provides your DNS service, and that is good, because they also are the authoritative body for your IP space. I found that out with this tool:

jim@jimsworktop:~$ dig -x

; <<>> DiG 9.4.1-P1 <<>> -x
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 25750
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;    IN      PTR

;; AUTHORITY SECTION:       10800   IN      SOA 3006103587 7200 1800 604800 172800

;; Query time: 464 msec
;; WHEN: Sun Nov 18 14:02:54 2007
;; MSG SIZE  rcvd: 133
Ok, so if you had a PTR it would have said in response to my question. You will have to have the PTR match the forward A map, which is for, not

So that server, needs to be the one configured to supply the PTR for your name.

To confirm that, we'll check and make sure the same company is authoritative for your address space -

jim@jimsworktop:~$ whois
% [ node-1]
% Whois data copyright terms

inetnum: -
netname:      Sabinfotech
country:      IN
descr:        Sabinfotech chandigarh
admin-c:      JK268-AP
tech-c:       JK268-AP
changed: 20060113
mnt-by:       MAINT-IN-BLAZENET
source:       APNIC

person:       Jitender Kumar
address:      SAB Infotech Ltd.
address:      S.C.O. 91-92, First Floor,
address:      Sector 8-C, Chandigarh - 160018
address:      India
country:      IN
phone:        +91-172-784162
fax-no:       +91-172-544983
nic-hdl:      JK268-AP
changed: 20010710
source:       APNIC
So yes, the people at need to create your PTR address. Contact them and ask for the PTR. Most ISPs have a webpage to make PTR requests, and once they get the request it is literally 30 seconds of work on their part. You should have a PTR in place within 24 hours.



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