about cache nonexist record

[Tech W.]

Hello,

I have Bind-9.6.1 running on our university environment, have been using dynamic update.

My question is, when other DNS query my named for a record, for example test.example.com, but this record doesn't exist. How long time will the remote DNS cache this nonexist record?

I found the problem that if this nonexist record was cached by remote DNS, even if I added the corresponding record to named zone soon, the remote DNS can't find it quickly.

This is not good for dynamic update IMO, for example, I need to change a record, then I have to do:

nsupdate delete ....
nsupdate add ....

If the remote DNS query for this record just after 'nsupdate delete', then it will get nothing and cache this nonexist record for some time, even though the correct record has been added. How to deal with this case?


Thanks.

Regards,
Wah.


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