On 05/16/2012 03:18 AM, Daniel Bossert wrote:
fedora skrev 16.05.12 10:33:
... or try dnsmasq
suomi
On 05/16/2012 08:54 AM, JD wrote:
On Tue, May 15, 2012 at 9:20 PM, Ed Greshko<Ed.Greshko@xxxxxxxxxxx>
wrote:
On 05/16/2012 10:11 AM, JD wrote:
I have nscd running.
/etc/resolv.conf starts out with
nameserver 127.0.0.1
nameserver 192.168.1.254
The 192.168.1.254 is the router, which has been a fast and reliable
resolver.
So, to test nscd caching behavior,
I browse (using FF) over to any website.
After some time, the address is resolved and the page comes up.
I kill the tab of the page, and open a new tab and aim the browser
at same url. Browser again says: looking up whatever....com and takes
several seconds to resolve it.
I thought that nscd is supposed to cache the translation from the
first lookup.
Am I to believe that the browser is NOT using /etc/resolv.conf?
If not, what is it using?
Or could it be that nscd is useless in this respect?
I've not looked at nscd in a long time....but I never could see the
value in it and
never could get it to what I thought was a working or useful
configuration for my needs.
No browser or application uses resolv.conf directly. They make
calls to the resolver
libraries which in turn use it.
IMO, if your router does caching name services there really is no
benefit to having
systems do their own caching since the overhead of local requests
should be small.
However, it seems that your router may not be caching since it is
taking several seconds.
In cases where the router isn't doing caching, or is doing it
poorly, I prefer to
simply run bind on a single server and point all the systems to it
for resolution.
With the current Fedora systems this is easy. All one need to do is
install bind and
bind-chroot and enable/start the service. On the "bind" host all
you need is
127.0.0.1 defined as a nameserver. Then, if you use a tool such as
"wireshark" you
will see that requests will only go out if the answer is not in the
cache or the TTL
has expired.
I understand the libs are what make calls to the resolver. But even
the resolver must look
at /etc/resolv.conf. If it is empty, NOTHING gets resolved.
I was using nscd thinking it is a lightweight caching resolver. But as
it turns out it is useless.
Time for fedora to bury it :)
Re: My router: it does very little if any caching - and has no
configuration for it at all.
I will try bind.
Thanx Ed.
JD
HI
Why do you have 127.0.0.1 in /etc/resolv.conf? Could it be that your
computer ask himself to resolv this ip and as he can't do that then he
get to your router and ask?
Do you have the same behaviour when only your router's ip adress is in
/etc/resolv.conf?
kind regards
Daniel
Well, if I recall correctly, using a caching dns daemon requires that
the first entry in /etc/resolv.conf be 127.0.0.1 followed by external
nameservers' ip addresses.
And yes, re: same behavior when only router's ip address is in resolv.conf.
As I indicated, the router does not seem to be caching anything, and I
believe
for good reason: reduce production cost - saving a few pennies per unit
can amount to millions of dollars. I have worked at industries that did
similar cost saving (or profit creating) design decisions. Just my
$.02's worth.
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