[SLL] Slow DNS lookups

[Mike Stunes]

Hmm... OpenDNS servers are definitely faster. Looking through our 
service status page, seems like they upgraded BIND at what seems to be 
about when I started noticing slowness...

Just got Ralph's comment--that would explain it.

Thanks, Derek, for your help!

Mike

Derek Simkowiak wrote:
>     Mike,
>     Thanks for posting the info.  Sorry for the slow reply... I'm in 
> the middle of building a new dev server...
>
> Mike>/ followed by an AAAA record lookup on <domain-name> + 
> ".mit.edu", followed by an A record lookup, which finally works. Don't 
> know if it did that before or not./
>
>     This happens because of the following line in your resolv.conf:
>
> search mit.edu
>
>     If you connect to a server called (e.g.) your_server.mit.edu, and 
> you only want to type "your_server", then DNS will automatically 
> figure out that "your_server" actually refers to the published I.P. 
> address of "your_server.mit.edu". 
>
>     But by default, the "search" option contains your local domain 
> name, which is already set to "mit.edu".  So this line is redundant on 
> your system (but causes no harm).
>
>     Regarding the speed of your DNS servers, I did find them to be 
> relatively slow (compared to my regular DNS servers).  But the 
> slowness I am experiencing might simply be because of where I am 
> physically located on the Internet; my ping time to your DNS servers 
> is about 102ms, and my ping time to my regular DNS servers is only 29ms.
>
>     Given that your slowness suddenly appeared last week, I suspect 
> that your DNS server administrators have made some change in the data 
> center.  Perhaps they installed a new (crappy) firewall, or changed 
> the routes in a way that makes it slow for you.  Or, maybe they've 
> installed Battlefield 2142 on the DNS servers, thinking nobody would 
> notice :)
>
>     To test that the problem is with your DNS servers (and not with 
> your computer), try temporarily replacing your resolv.conf with the 
> following text:
>
> domain mit.edu
> search mit.edu
> nameserver 208.67.222.222
> nameserver 208.67.220.220
>
>     ...and then surf the web and see if it's faster.  (Those new 
> nameservers are the OpenDNS servers.)
>
>     If it's faster, call the sysadmins at MIT and tell them to 
> uninstall Battlefield off the DNS servers.
>
> --Derek
>
>
> Mike Stunes wrote:
>> # Generated by net-scripts for interface br0
>> domain mit.edu
>> search mit.edu
>> nameserver 18.70.0.160
>> nameserver 18.71.0.151
>> nameserver 18.72.0.3
>>
>>
>> Derek Simkowiak wrote:
>>>     Can you post your /etc/resolv.conf?
>>>
>>>     If they're publicly available, I'll switch to your DNS servers 
>>> and see if I can reproduce the symptoms.
>>>
>>> --Derek
>>>
>>> Mike Stunes wrote:
>>>> Recently I've been having an issue with name lookups, particularly 
>>>> from Firefox, taking much longer than they used to. Seems like it 
>>>> used to be pretty quick, and now navigating to a different site 
>>>> takes several seconds, usually about four or five. (If I remember 
>>>> right, this has been going on for a few days, maybe a week or so.) 
>>>> Once Firefox gets past "Looking up ...", however, it's a breeze. I 
>>>> can't figure out what might have changed that would cause this--I 
>>>> don't remember having done any major software updates or config 
>>>> changes about the time this started, and /etc/hosts and 
>>>> /etc/resolv.conf look fine. Wireshark shows an interesting story-- 
>>>> first, an AAAA record lookup, followed by an AAAA record lookup on 
>>>> <domain-name> + ".mit.edu", followed by an A record lookup, which 
>>>> finally works. Don't know if it did that before or not. Does anyone 
>>>> have any idea what might be going on? Thanks in advance!
>>>>
>>>> Mike
>>>
>