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cdns.ovh.net


darkfyre
19-08-2009, 15:23
yup

i do the same

But cdns.ovh.net had an expired ttl on 94.23.159.17 so is giving the correct reverse of mail.nullroutes.com to anyone who queries it.

However

If i do the query from ks25131.kimsufi.com i get the old answer of 94-23-159-17.kimsufi.com. (even tho the ttl expired twice already since i noticed this problem)

thats what im trying to explain .. there is a problem with cdns.ovh.net giving one host stale records.

Ill wait until the ttl on the reverse expires for the 3rd time (in about 4 hours - set by OVH and not me) - and pray it updates itself.

freshwire
19-08-2009, 15:04
I don't know about your PTR records but for records A/MX/TXT I have stored locally they are set with TTL at 3600 so after just 1 hour all dns caches should drop the older records. The TTL is specified when you declare your PTR record... wherever that may be..

darkfyre
19-08-2009, 13:49
the record isnt coming from a root server, the reverse is deligated to ovh's server and its a stale record from them not the root server. anyone else in ovh's network who uses this server will get the correct record apart from my server for some reason.

I think they must run some sort of funky cache with a cache per mac or Ip or who knows what and its not a cache locally on my server, its a fresh packet coming from ovh's dns server (see previous post with packet )

derchris
19-08-2009, 13:48
Well, the local DNS updates it maybe within minutes.
But DNS takes 24-48 hrs until it is propagated to all the other root servers.

darkfyre
19-08-2009, 13:48
i do and i use it..

but i prefer consistency from servers - hence why I do a check on most dns servers I use 24 hours after making a change.

ovh is the only cache to retain the old information and only provide it to one server while giving the new records to anyone making a fresh query ..

kinda stange huh

freshwire
19-08-2009, 13:46
Then setup your own cache

darkfyre
19-08-2009, 13:38
seems very 1980's to have a cache holding records for 24 hours these days.

Every other dns server on the internet that I have used updated my changes within minutes :-(

freshwire
19-08-2009, 13:37
According to the TTL it will expire in 5.6 hours anyway. In that time its unlikely you will get a response from OVH. You can always configure the servers to use another dns maybe local dns cache?

darkfyre
19-08-2009, 13:35
Yes im 100% sure, its a stale record in cdns.ovh.net

Ive seen the packets and read them, cdns.ovh.net is providing the information which is old and stale.

however it will only provide this stale record to ks25131.kimsufi.com so i think their cache server runs per IP/infrastructure/router.on.a.stick cache ?

darkfyre
19-08-2009, 13:34
; ANSWER SECTION:
17.159.23.94.in-addr.arpa. 20732 IN PTR 94-23-159-17.kimsufi.com.

freshwire
19-08-2009, 13:32
;; ANSWER SECTION:
17.159.23.94.in-addr.arpa. 86400 IN PTR mail.nullroutes.com.

Requested from 91.121.175.121.

Just lets try this command to be sure:

$ dig @213.186.33.99 -x 94.23.159.17

darkfyre
19-08-2009, 12:32
Just to confirm that am I not using an caching software - here is a dump of the traffic coming back from cdns.ovh.net

12:30:17.969346 IP (tos 0x0, ttl 64, id 58460, offset 0, flags [none], proto UDP (17), length 71) jammy.nullroutes.com.63720 > cdns.ovh.net.domain: [udp sum ok] 49167+ PTR? 17.159.23.94.in-addr.arpa. (43)

12:30:17.969707 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto UDP (17), length 155) cdns.ovh.net.domain > jammy.nullroutes.com.63720: [udp sum ok] 49167 q: PTR? 17.159.23.94.in-addr.arpa. 1/2/0 17.159.23.94.in-addr.arpa. PTR 94-23-159-17.kimsufi.com. ns: 159.23.94.in-addr.arpa. NS dns15.ovh.net., 159.23.94.in-addr.arpa. NS ns15.ovh.net. (127)
Is it possible for the cache on cdns.ovh.net to be flushed ? as its holding stale information .. but its only stale if the request comes from jammy.nullroutes.com

darkfyre
19-08-2009, 12:17
Im having a strange issue using cdns.ovh.net

If I reverse resolve 94.23.159.17 from any DNS server is translates to mail.nullroutes.com

control# host 94.23.159.17
17.159.23.94.in-addr.arpa domain name pointer mail.nullroutes.com.
control#
However when I use cdns.ovh.net to resolve it, the answer is:

jammy# host 94.23.159.17
17.159.23.94.in-addr.arpa domain name pointer 94-23-159-17.kimsufi.com.
Furthermore, If I use cdns.ovh.net from another dedicated server it resolves correctly to mail.nullroutes.com. It is only when I initiate the query from ks25131.kimsufi.com that the old record of 94-23-159-17.kimsufi.com shows.

I do not run any caching software and have captured DNS packets leaving and coming into my machine, cdns.ovh.net is in fact supplying 'fresh' dns information to my server each time with the wrong result.

Why is it that cdns.ovh.net shows the correct entry to all my servers who done the query after the dns change was made, but on the server which made a query before the change was made its still getting stale information?

I assumed cdns.ovh.net had a cache per server??, but its been 12 hours now so I thought it would have updated ..