Re: Non-existent zone file

On Thu, Dec 3, 2009 at 12:24 PM, Rich Rumble <[email protected]> wrote:
> We were inundated with request for a domain we didn't have in the cdb,
> and the NS's became very sluggish, but bandwidth wasn't too high... so
> perhaps tinydns was dropping the requests, but the process was clearly
> the highest in use in top for that period. We sniffed the requests and
> saw 99% were looking for a name we didn't have, a whois indicated that
> someone pointed the domain at our NS's. Perhaps it was just ironic
> timing... we figured we'd create a zone and point it to maintenance
> page, once we did the load went way down and so to did the
> connections, were still trying to get a better understanding of what
> happened, were not certain our actions of creating the file and
> make'ing the cdb were the actual fix or if it just subsided at that
> same time.
> -rich

I suppose tinydns doesn't know what it is and is not authoritative for
until it checks the cdb.  Stock djbdns-1.05 is going to mmap/munmap
data.cdb once per request.  That can get expensive in terms of CPU
time if your incoming query rate is high enough.  If you search the
mailing list archives:

http://marc.info/?l=djbdns

You'll find multiple discussions about the expense of opening data.cdb
once per request and a least one patch that you may find useful (which
I've merged into my fork of djbdns).