Re: BIND-DLZ cache corruption issue.

DLZ uses the same functions BIND does for 'loading' zone data.  The only 
difference is this 'loading' is done on demand instead of on startup.

It shouldn't have affected your cache, as records from DLZ shouldn't be in the 
BIND cache.  Are you sure the truncated record was the root cause?

Rob


>
>From: Michael J. Ayers <[email protected]>
>To: bind-dlz-testers <[email protected]>
>Sent: Wed, September 29, 2010 5:18:21 PM
>Subject: [Bind-dlz-testers] BIND-DLZ cache corruption issue.
>
>Hey all,
>
>
>We recently ran into an issue where BIND-DLZ incurred complete cache corruption 
>due to a single bad entry in our zone.  We had an TXT/SPF record in our zone 
>that was accidentally set to over 255 characters in length.  When the record was 
>looked up and cached, BIND apparently read the first 255 bytes of the record and 
>then truncated the rest (including the closing quote) off.  This had the affect 
>of making the entire cache unusable.  Symptoms were initial lookups would work 
>with a small delay in the lookup while cache was checked, however all subsequent 
>requests for cached entries would not return a result.  This made our DNS 
>completely unusable until the issue was tracked down.
>
>
>I know that there should be some sort of check in the data entry/management 
>application for the zone to validate that records entered in are correct, 
>however does it not make sense to do some sort of per entry check to make sure a 
>record is valid prior to accepting and returning a response to the request. 
> BIND traditionally checks for these type of issues at startup, however when 
>utilizing DLZ this startup check is bypassed.  I guess I am requesting that some 
>form of record/entry checking be added to the code to prevent issues which might 
>make DNS completely unavailable.
>
>
>Thoughts?
>
>
>--M
>
>-- 
>Michael J. Ayers
>Senior Systems Engineer
>

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