Re: Unusable DNS, 10.4 Tiger (Big Breakthrough)
Re: Unusable DNS, 10.4 Tiger (Big Breakthrough)
- Subject: Re: Unusable DNS, 10.4 Tiger (Big Breakthrough)
- From: email@hidden
- Date: Thu, 8 Dec 2005 14:56:12 -0700
On Dec 2, 2005, at 7:21 AM, Peter Sichel wrote:
I've written Zack directly, but wanted to add a couple observations
since sharing one's ignorance in public is a great way to learn :-)
(2) Can you isolate the problem to the local DNR (Domain Name
Resolver)
Hi all, sorry for my late response, I have just been really busy this
week. I have tried all of your suggestions but unfortunately I
either don't know enough about configuring this stuff, or all of them
are running through the same services so suffer from the 5 second
delay still.
I've had a big breakthrough though finally, in that I found a way to
do fast lookups, and maybe someone here can help me apply this to my
whole system. If I type these, where 205.171.2.65 and 205.171.3.65
are Qwest's DNS servers, which I also have set in my Network control
panel, I get:
host -T -v ants.com
...
Received 167 bytes from 205.171.2.65#53 in 64 ms
Is instant.
host -T -v bears.com 205.171.2.65
...
Received 106 bytes from 205.171.2.65#53 in 120 ms
Is instant.
host -v cats.com
Trying "cats.com"
(!!!!! 5 second delay !!!!!)
...
Received 42 bytes from 205.171.3.65#53 in 139 ms
So the response was instant, but something in the OS was holding the
response for 5 seconds.
nslookup dogs.com 205.171.2.65
Takes 5-7 seconds.
I think what is happening here is, "host -T domain.com" opens a TCP
connection to the name server, and for whatever reason, this is much
faster than using UDP. I don't think this is inherent to UDP, I
think it is more about how often the system re-queries, since UDP is
unreliable, and either arrives in milliseconds or does not. Also, on
DSL, UDP should be 99% reliable, so I also think that the UDP pathway
in DNS lookups is stalling somehow. I can't tell a difference using
a specific name server vs having host use the default name servers I
have set.
On Dec 2, 2005, at 1:06 AM, Justin C. Walker wrote:
Bind can be configured to use TCP for queries (cf. the RES_USEVC
option for the resolver (in <resolv.h>).
Regards,
Justin
Is this just for programming, or an option I can set system-wide?
Anyway, I think something is wrong with nslookup and lookupd, that
whole pathway, at least for UDP. Seeing delays of 2-3 seconds at any
step of the way is completely unacceptable on DSL, where I can get
ping times of 30ms, 150kB/sec downloads, etc. Lookupd should perhaps
monitor itself and if it ever takes longer than a few milliseconds to
do anything, log that as an error in and of itself.
Can someone tell me how to fix this problem, or use TCP instead of
UDP for DNS lookups?
Thank you,
------------------------------------------------------------------------
Zack Morris Z Sculpt Entertainment This Space
email@hidden http://www.zsculpt.com For Rent
------------------------------------------------------------------------
If the doors of perception were cleansed, everything would appear to man
as it is, infinite. -William Blake, The Marriage of Heaven and Hell
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