Clearing DNS Cache frequently

[Andy Harlan]

Hello,

Every week or so usually for a couple days in a row our
clients will no longer be able to connect to their mail
server(ISP) which they are POPing through Outlook. In
order for them to reconnect to the mail server I have to
go onto the DNS server and in admin tools->DNS I will
right click on our DNS server and clear the cache which
allows everyone to connect again. I have checked and
this IP address of this mail server has not been changing
yet we have to clear the cache in order to connect to
it. This usually happens a couple days in a row and then
it is alright for a week or so.

Do you have any suggestions or is there any way I can
trouble shoot this problem.

Thanks.

 

[Herb Martin]

Every week or so usually for a couple days in a row our

clients will no longer be able to connect to their mail
server(ISP) which they are POPing through Outlook. In
order for them to reconnect to the mail server I have to
go onto the DNS server and in admin tools->DNS I will
right click on our DNS server and clear the cache which
allows everyone to connect again. I have checked and
this IP address of this mail server has not been changing
yet we have to clear the cache in order to connect to
it. This usually happens a couple days in a row and then
it is alright for a week or so.

First thing I would do is actually view the cache (View\Advanced
in the MMC GUI) to find out if a bad value is actually IN THERE
or if clearing the cache is having some secondary (perhaps
undocumented or accidentally) effect.

Second, I would double check the "service pack/hot fix status"
of the servers involved.

Third, I would make sure the cache was secured against polution,
DNS server Properties\Advanced check box -- although that is
unlikely to be the source of a problem it might as well be eliminated.

(I am still trying to find a really good reason for not doing the latter
always.)

 

[William Stacey]

When it fails, I would also do a dig or nslookup against the dns server for
that name and see what IP you get back. This could help verify if it is a
polution issue.
--wjs

 

[Herb Martin]

The point was to wait until the problem reoccurs, then
view the cache to see if there is anything odd in there....

Of course items expire, that is what TTL settings are for:
How long may someone else cache a record...