Name résolution

[Guillou_2]

Hi,

During test we changed the name of a server and after we came back to its original name.
Since this operation when we do a telnet to another server, on some of them, a "sho user/full" shows something like:
username _TNA4458: 00041EAB TNA4458: (Host: old name Port: 3749 )

a "set host" shows the right name for the source.

The configuration of TCPIP seems to be good

Any idea

regards

Steph

[Ian Miller.]

Are you saying that on the remote system the name shown from telnet connections from that server is incorrect?
It could be a name translation cache needs flushing to remove the incorrect translation.

[Guillou_2]

I initiate a connection from the server A, the server which name has been changed, to server B. On server B the source of the connection isn't the new name but the old of server A.
This behaviour is seen only with a telnet connection not with a set host.

[Ian Miller.]

Are both nodes using the same DNS server or local host files? I'm just wondering if host B backtranslates the incoming IP address using some out of date information.

[Kris Clippeleyr]

Steph,

Did you check the host database on the server?
TCPIP SHOW HOST /LOCAL

Maybe some stale data was left in there.

Greetz,

Kris

[Guillou_2]

The local base is not used for the translation, we use DNS.

[Ian Miller.]

Are both nodes using the same DNS server? I still suspect the old name is cached somewhere.

[Bojan Nemec]

Steph,

My oppinion is the same a s Ians. The old name is cached somewhere.

Did you try to do a
TCPIP> SET NAME_SERVICE/INITIALIZE
on all nodes which are running DNS? This command reloads the BIND database.

Bojan

[Guillou_2]

Servers use the same primary DNS, the second is different.

We use DNS implemented on Unix server, so a set name/init doesn't help.

I tried to stop and restart the UCX/TCPIP service on the server which received the connection, the problem seems to "run away".
The wrong information seems to be cached, but where?
Is there a TCPIP/UCX command to "flush" this cache like in Decnet/OSI?

[Ian Miller.]

Parhaps this may clear the cache?
UCX
SET NAME/SYSTEM/DISABLE
SET NAME/SYSTEM/ENABLE

I'm not aware of a command to flush the name resolver cache.

Do you mean the first DNS server listed for each system (UCX SHOW NAME) is the same?

[Bojan Nemec]

I try to find if there is a command to flush the cache, but find nothing.

Just curiosity, have you try to do a telnet old_name from the server which shows the old name?

Bojan

[Ian Miller.]

You could use NSLOOKUP to query the different servers to see which is returning the old name and get that one to reload. The cached entry wherever it is will expire when the TTL for the name is reached.

[Guillou_2]

Hi Bojan,

a telnet old name gives "%TELNET-E-IVHOST, Invalid or unknown host"

all the entry concerning the old name were removed from the dns

Hi Ian

enabling/disabling doesn't solve the problem

Thanks for your help I will stop/start the ucx/tcpip service to correct my problem

Steph.