DNS

[Nobody's Hero]

My wins guy wants me to change all my HPUX boxes to point to a new DNS server.

When I change the entries in /etc/resolv.conf
DO I have to reboot for the changes to take effect or is it dynamic?

[James A. Donovan · Accepted solution]

You do not have to reboot.

[Steven E. Protter]

Shalom Robert,

You can test it too.

make the change

nslookup hp.com
dig yahoo.com

You will see immediate results.

SEP

[Geoff Wild]

No need to reboot, no need to restart any services...

Just a tip though, in Unix, we always check the first DNS server in resolv.conf - which means every DNS lookup will fail ( and wait 5 seconds and try 4 times!!) if that server is down.

So, in resolv.conf:

retrans 2500
retry 2

retrans

Retransmission timeout. It is interpreted during
the res_init() (see resolver(3N)) call. It has
higher precedence than setting it through the
set_resfeild() (see resolver(3N)) API and lower
precedence than setting it through the RES_RETRANS
(see resolver(3N)) environment variable. Whenever
an invalid value is specified for retrans, a
message is flagged in syslog. The default value
is 5000 milliseconds.

retry

Number of retries. This is interpreted during the
res_init() (see resolver(3N)) call. It has higher
precedence than setting it through the
set_resfeild() (see resolver(3N)) API and lower
precedence than setting it through the RES_RETRY
(see resolver(3N)) environment variable. Whenever
an invalid value is specified for retry, a message
is flagged in syslog. The default value is 4.


That will speed up any delays going from 1 nameserver to another - unfortunately, Windows does a better job - if it can't get to the first one, it goes to the second - if successful, it's next query will automatically go to the second. In unix, this is not the case - we will always try the nameservers in order based on resolv.conf.


Rgds...Geoff