[Techtalk] dns issue

Maria Mckinley maria at shadlen.org
Thu Jan 12 19:46:30 UTC 2012

Hello everyone,

The problem was most definitely with my registrar, and their dns 
servers. They were either not responding at all, or not giving answers 
if they were. However, several issues have been raised that I am curious 
about. Weirdly, at this point, mail is being delivered, but dns lookups 
are still not always giving an answer.

First, regarding the A record for dns.shadlen.org, it is available both 
from dns.shadlen.org and ns#.mydomain.com (which are run by my 
registrar, and there are several ns1, ns2, etc.), and they are all 
legitimate name servers for my domain; however yesterday the name 
servers at mydomain were not working properly, and my server was 
experiencing a recursive problem. The recursive problem being that cache 
for the ip of my dns server on servers worldwide had expired, and the 
registrar's dns was not working, so no one could actually use my dns 
server, not knowing its ip. Is there anyway to get around this problem? 
Is there even any point to me running my own dns server as a backup if 
it is unusable, when my registar's dns servers go down?

There was also an incorrect ip for my dns server floating around, and 
this seemed to come from a reverse lookup that my university failed to 
delete years ago. It was not a problem until now, I suppose because the 
lookup and reverse lookup always worked with the actual, current ip 
until yesterday. They have now deleted this reverse lookup, so this 
should not be a problem anymore. I hope.

Lastly, Susan brought up a situation with my web server and smtp server, 
which is that they share an ip address. Is this really a problem? They 
have had the same ip address for years. Neither smtp nor www.shadlen.org 
have MX records, only mail.shadlen.org as the mail server has one, and 
it is for the name, not the ip, which is in the corresponding A record. 
In fact, there are several other domain names using this ip, but none of 
them have MX records, only A records.

thanks for everyone's help,


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