On Mon, 23 Aug 2010, Tom H wrote:
To: CentOS mailing list <centos@xxxxxxxxxx>
From: Tom H <tomh0665@xxxxxxxxx>
Subject: Re: Slow domain resolution problem
On Mon, Aug 23, 2010 at 9:48 AM, Giles Coochey <giles@xxxxxxxxxxx> wrote:
The problems can sometimes be caused by not having reverse-DNS records for
your hosts. Can you resolve to names (any name) from an IP address?
e.g. nslookup 10.2.9.2?
If this is a reverse-lookup problem and you can't have a
reverse-lookup zone (I worked at a company where the Windows admins
refused to create one when we asked them to do so!), you can add
"[NOTFOUND=return]" to the hosts line in nsswitch.conf after "dns"
otherwise your dns server will forward the query out to the net
(assuming that your egress rules allow it to do so) and an answer will
be returned by the some servers set up for this purpose on the net -
called blackhole-something, IIRC.
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Not sure if it is RDNS.
I had similar issues on Fedora, and for me it was to do with
IP6.
Konqueror web browser took ages to load a page. IIRC Firefox
handled it OK.
Try Googling for 'uninstalling ipv6 linux'
That solved the Konqueror DNS problem for me. Yours could be
a different issue.
Here's the results of going to the ShieldsUp page at
https://www.grc.com/x/ne.dll?bh0bkyd2
Your Internet connection has no Reverse DNS
Many Internet connection IP addresses are associated with a
DNS machine name. (But yours is not.) The presence of
"Reverse DNS", which allows the machine name to be retrieved
from the IP address, can represent a privacy and possible
security concern for Internet consumers since it may
uniquely and persistently identify your Internet account —
and therefore you — and may disclose other information, such
as your geographic location.
When present, reverse DNS is supported by Internet service
providers. But no such lookups are possible with your
current Internet connection address (81.168.74.150). That's
generally a good thing.
Another thing is how many DNS IP addresses do you have in
/etc/resolv.conf?
I only had one DNS IP address thanks to NetworkManager on
F12. And that DNS host went down at my ISP end!
I use four IP addresses now in my reslov.conf file.
Kind Regards,
Keith Roberts
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