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Obsolete Releases => SME Server 7.x => Topic started by: nicksin on June 28, 2006, 09:33:59 AM

Title: Very slow DNS response
Post by: nicksin on June 28, 2006, 09:33:59 AM: Hi All.

I seem to have picked up a funny. Not too sure if its a bug or possibly a config issue so Ill post here first.

I have a SME server version 7 rc 2. It sits in a DMZ as a mail and DNS Server.
Im getting a very delayed response from the server when it needs to resolve a name that doesnt seem to be cahced.
For example doing a dig for yahoo times out 1st time and 2nd time goes through immediately.

Querying a remote dns server responds very fast. I had a look at the line utilization and it is not related to congestion etc.

Any ideas / help will be greatly appreciated.

Thanks and Regards
Nic

dig @10.10.9.5 www.yahoo.com

; <<>> DiG 9.3.1 <<>> @10.10.9.5 www.yahoo.com
; (1 server found)
;; global options: printcmd
;; connection timed out; no servers could be reached

dig @10.10.9.5 www.yahoo.com

; <<>> DiG 9.3.1 <<>> @10.10.9.5 www.yahoo.com
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32366
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.yahoo.com. IN A

;; ANSWER SECTION:
www.yahoo.com. 257 IN CNAME www.yahoo.akadns.net.
www.yahoo.akadns.net. 36 IN A 209.73.186.238

;; Query time: 0 msec
;; SERVER: 10.10.9.5#53(10.10.9.5)
;; WHEN: Wed Jun 28 09:31:36 2006
;; MSG SIZE rcvd: 81
Title: Very slow DNS response
Post by: compsos on June 28, 2006, 02:22:33 PM: We have been seeing something similar with 2 way satellite and thought it might be external. But your post sounds similar.
The client machines time out trying to get webpages but do get the page on the refresh.
Have you found any solutions?
Title: Very slow DNS response
Post by: nicksin on June 28, 2006, 02:26:57 PM: Nothing as yet,

Been considering moving from rc 2 to rc 3, otherwise downgrading to 6.x might be an option.
What version are you using ?

Rgds
Nic
Title: Very slow DNS response
Post by: compsos on June 28, 2006, 03:15:44 PM: Nic
We are using 7rc3. Have also noticed on yum updates timeouts and failures but think this is the satellite latency.
What tests did you do on your system I will try to duplicate.
Title: Very slow DNS response
Post by: compsos on June 28, 2006, 03:29:04 PM: Nic
I just stopped the dnscache and then tried a dig it failed restarted the cache and response was a lot better. Would need more extensive testing. Could it be a stale cache?
Title: Very slow DNS response
Post by: chris burnat on June 28, 2006, 04:51:22 PM: This sort of issues should really be posted on the Bugtracker. (i) they can be investigated and resolved (i) they are on the records - posts in this forum tends to get lost after a while. Thanks on behalf the dev team.
Title: Very slow DNS response
Post by: compsos on June 28, 2006, 11:42:39 PM: We have not sent it to bugtracker as yet mainly because we need to confirm if it is SME or external. In our case the 2 way satellite has its own latency and weather problems that can affect performance.
Does anyone know a good test routine to isolate the point of delay for this type of issue?