Reasons for not resolving

[Kevin Darcy]

Alans,
Why would you use Google to determine whether a web site is up or not?

It's not even clear to me that you're having a DNS problem. It's rather 
bad practice to have lots of reverse-records in the DNS for a given 
address (e.g. 96.31.75.113), and can even cause problems with oversized 
responses to reverse lookups being dropped by firewalls, but it 
shouldn't cause any *forward* (name-to-address) lookups to fail.

Can you resolve a name like yarnandwaste.com or can't you? Please follow 
normal diagnostic procedures and try to determine what actual problem 
you are having. "Can't ping or browse" is only the start of the 
diagnostic process, and might not be caused by DNS at all.

Once you've determined that you can't resolve a particular name, then 
something you might try is a "dig +trace" on the name, from your 
nameserver. That will show you the sequence of queries that will be 
followed by a resolver to try and resolve the name, and might help 
pinpoint the source of the problem. It will not, however, exactly match 
what your nameserver is doing unless you have a completely "vanilla", 
iterative-resolving configuration (i.e. Internet root hints and nothing 
else). If you have other elements of your config that affect resolution, 
e.g. zones of type stub/forward/master/slave anywhere in the hierarchy 
of the name you're looking up, or "forwarders" in your "options" clause, 
then "dig +trace" won't know about those "specials" and can't match 
exactly what your nameserver would do. Also, it's possible that your 
nameserver has cached data that might cause it to resolve differently 
than "dig +trace", which always starts with no cache at all.

- Kevin

Alans wrote:
>
> I looked more and I figure out that we can’t ping or browse any of 
> these hosts http://www.ip-adress.com/reverse_ip/96.31.75.113 (they all 
> are on one IP) it’s confusing because when I search in google for host 
> names it appears in the result which means it’s not down fir 
> everyone!! Any ideas?
>
> Kind regards,
>
> Alans
>
> *From:* bind-users-bounces at lists.isc.org 
> [mailto:bind-users-bounces at lists.isc.org] *On Behalf Of *Alans
> *Sent:* Wednesday, October 28, 2009 10:47 AM
> *To:* bind-users at lists.isc.org
> *Subject:* Reasons for not resolving
>
> Hello,
>
> There are few websites that our DNS (BIND 9.4.2 on CentOS 5) is not 
> resolving while others like 4.2.2.2 does, I wonder what could be the 
> reasons for this?
>
> Regards,
>
> Alans
>
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