Fedora Account System
Red Hat Associate
Red Hat Customer
Description of problem: I am having trouble with slow DNS lookups. I have investigated the issue and I cannot find any reports for something quite similar. I am still on Fedora 10, and don't have the opportunity to upgrade just to test if this has been resolved on F11, so I am reporting this, although it might be fixed already in F11. I recently switched to a new router, a D-Link DIR-855, which has triggered this behaviour. I did not see the behaviour on my old router. I am uncertain whether the fault is in the router, or in the fedora distribution. I have a workaround, which might help other affected. What happens is that if I am trying to reach a host, for example, example.com in any application, DNS lookup for the hostname is slow. Using wireshark I can see that the resolver sends the following queries AAAA example.com AAAA example.com.localdomain A example.com The AAAA example.com.localdomain is really slow. I get this delay for each use of normal ipv4 hosts, since none of those AAAA hosts exist. Further, if example.com does not exist, there is an additional "A example.com.localdomain" done as well before it finally fails. The /etc/resolv.conf which is created by NetworkManager is simply: # Generated by NetworkManager nameserver 10.0.1.1 on both the old and the new router. I have not investigated in detail which queries were done on the old router, but if you think it would help, I can do that for you. Let me know. I have fixed it by installing a file /etc/dhclient-eth0.conf with the following contents: supersede domain-search " ."; supersede domain-name " ."; and I don't get the really slow *.localdomain queries. Windows and Ubuntu doesn't seem to be affected by this. As I said, I don't understand the issue well enough to know where to put the blaim, but I thought I will report it here anyway, in case someone else is affected, and maybe you can tell what is wrong and fix the issue, if it is a problem in fedora. Version-Release number of selected component (if applicable): $ uname -sr Linux 2.6.27.30-170.2.82.fc10.i686 $ rpm -q glibc glibc-2.9-3.i686 How reproducible: Steps to Reproduce: 1. Start up computer in network 2. browse web 3. Actual results: Web is really slow because of slow DNS lookups Expected results: Web should be fast. Additional info:
I have investigated this more, and it appears that the router is dropping DNS queries which would result in NXDOMAIN. This is probably the main issue, though performance would be fixed if glibc would run the different queries concurrently.
This might be a duplicate of bug 505105. With my 2wire router, many DNS lookups fail. When I switch to my Netgear router, DNS lookups succeed, but they are often very slow (taking several seconds as opposed to a fraction of a second). The problems disappear when I disable IPv6 or switch to DNS servers provided by OpenDNS.
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Fedora 10 changed to end-of-life (EOL) status on 2009-12-17. Fedora 10 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. Thank you for reporting this bug and we are sorry it could not be fixed.