PTR problem

csdhiman · 11-17-2007, 02:00 AM

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 202.131.124.4
Secondry DNS 202.131.124.5

Mai Server IP : 202.131.114.7
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 202.131.114.7 is
Server: ns.glide.net.in
Address: 202.131.124.4

Name: mailsswl.sswlindia.com
Address: 202.131.114.7

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 arp.net root server or the problem is on our end .

dkm999 · 11-17-2007, 07:31 PM

From here, it appears the problem is a configuration problem at your end. As you said, the name mailsswl.sswlindia.com does resolve to the address 202.131.114.7. However, your MX record for sswlindia.com does not give that name. Instead, it
contains the name mail.sswlindia.com.

Further, the address 202.131.114.7 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 gw1.glide.net.in.

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.

JimBass · 11-18-2007, 01:20 PM

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 -

Code:

jim@jimsworktop:~$ dig mailsswl.sswlindia.com

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

;; QUESTION SECTION:
;mailsswl.sswlindia.com.                IN      A

;; ANSWER SECTION:
mailsswl.sswlindia.com. 86400   IN      A       202.131.114.7

;; AUTHORITY SECTION:
sswlindia.com.          86400   IN      NS      ns1.glide.net.in.
sswlindia.com.          86400   IN      NS      ns.glide.net.in.

;; ADDITIONAL SECTION:
ns.glide.net.in.        86399   IN      A       202.131.124.4
ns1.glide.net.in.       86399   IN      A       202.131.124.5

;; Query time: 796 msec
;; SERVER: 192.168.68.103#53(192.168.68.103)
;; 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 glide.net.in 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:

Code:

jim@jimsworktop:~$ dig -x 202.131.114.7

; <<>> DiG 9.4.1-P1 <<>> -x 202.131.114.7
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 25750
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;7.114.131.202.in-addr.arpa.    IN      PTR

;; AUTHORITY SECTION:
202.in-addr.arpa.       10800   IN      SOA     ns1.apnic.net. read-TXT-record-of-zone-first-dns-admin.apnic.net. 3006103587 7200 1800 604800 172800

;; Query time: 464 msec
;; SERVER: 192.168.68.103#53(192.168.68.103)
;; WHEN: Sun Nov 18 14:02:54 2007
;; MSG SIZE  rcvd: 133

Ok, so if you had a PTR it would have said mailsswl.sswlindia.com in response to my question. You will have to have the PTR match the forward A map, which is for mailsswl.sswlindia.com, not mail.sswlindia.com.

So that server, ns1.apnic.net 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 -

Code:

jim@jimsworktop:~$ whois 202.131.114.0
% [whois.apnic.net node-1]
% Whois data copyright terms    http://www.apnic.net/db/dbcopyright.html

inetnum:      202.131.114.0 - 202.131.114.255
netname:      Sabinfotech
country:      IN
descr:        Sabinfotech chandigarh
admin-c:      JK268-AP
tech-c:       JK268-AP
status:       ASSIGNED NON-PORTABLE
changed:      rajeev@blazenet.biz 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
e-mail:       jitender@glide.net.in
nic-hdl:      JK268-AP
mnt-by:       MAINT-IN-SABINFOTECH
changed:      jitender@glide.net.in 20010710
source:       APNIC

So yes, the people at glide.net.in 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.

Peace,
JimBass