Re: nscd and DNS cache

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



... 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
--
users mailing list
users@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe or change subscription options:
https://admin.fedoraproject.org/mailman/listinfo/users
Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Have a question? Ask away: http://ask.fedoraproject.org


[Index of Archives]     [Older Fedora Users]     [Fedora Announce]     [Fedora Package Announce]     [EPEL Announce]     [EPEL Devel]     [Fedora Magazine]     [Fedora Summer Coding]     [Fedora Laptop]     [Fedora Cloud]     [Fedora Advisory Board]     [Fedora Education]     [Fedora Security]     [Fedora Scitech]     [Fedora Robotics]     [Fedora Infrastructure]     [Fedora Websites]     [Anaconda Devel]     [Fedora Devel Java]     [Fedora Desktop]     [Fedora Fonts]     [Fedora Marketing]     [Fedora Management Tools]     [Fedora Mentors]     [Fedora Package Review]     [Fedora R Devel]     [Fedora PHP Devel]     [Kickstart]     [Fedora Music]     [Fedora Packaging]     [Fedora SELinux]     [Fedora Legal]     [Fedora Kernel]     [Fedora OCaml]     [Coolkey]     [Virtualization Tools]     [ET Management Tools]     [Yum Users]     [Yosemite News]     [Gnome Users]     [KDE Users]     [Fedora Art]     [Fedora Docs]     [Fedora Sparc]     [Libvirt Users]     [Fedora ARM]

  Powered by Linux