DNS Query Question

Stephen Satchell list at satchell.net
Wed Jan 24 02:07:51 UTC 2007

Dennis Dayman wrote:
> I have a customer having some DNS issues. They have done some research
> regarding some DNS timeout errors they saw with Verizon's sender verify
> looking up their MX records. What they have discovered is their current 
> DNS service has a 1% failure/timeout rate. They are exploring other 
> vendors (UltraDNS for one), but need an estimate of the number of DNS 
> queries for accurate pricing to put together a ROI argument for the
> switch.

I had some problems with DNS timeout, and discovered that by doing 
priority queuing in my Cisco routers I was able to cut the failure rate 
to my authoritative DNS servers to near zero.  The only time my DNS 
servers don't give a proper response is when a router is being flooded 
with other outbound data.

Is your customer using BIND?  What do the statistics tell you?  How many 
DNS servers are handling the traffic?  Are they load-balanced?  Has the 
DNS servers been upgraded to handle more traffic?  Does the customer 
segregate their authoritative servers from their recursive ones?  (That 
one change right there improved my DNS reliability and servicability by 
several orders of magnitude!)

 From your description, I'd say there was a lot more work to be done 
first, unless they just don't have the people to do it right.

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