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MazdajaiFlag for United States of America

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DNS server query - zone verus cache

A simple DNS question that may sound silly -

The below explanation is from Microsoft official url explaining DNS process -

Shouldn't it always check the cache first before looking up the zone? In my understanding, it should always look up cache first because is faster, like using local resolver?

How DNS query works

https://technet.microsoft.com/en-us/library/cc775637%28v=ws.10%29.aspx

When the DNS server receives a query, it first checks to see if it can answer the query authoritatively based on resource record information contained in a locally configured zone on the server...

If no zone information exists for the queried name, the server then checks to see if it can resolve the name using locally cached information from previous queries.
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RichardPhippen
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On your local network, your DNS server is the authoritative server. You Look up servername.domain.local, it looks to itself to resolve it. If you look up www.domain.com it will look to its self fail, then look at cache, if someone else recently looked up the same domain it will have it cached, if not then it goes to whatever forwarding DNS server you have set in MSDNS.
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footech
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Sorry for the delay and thanks for the responds!

I thought looking up cache would be a faster operation. (without getting the network layer involved)

I guess this is for what Caching DNS for? :)
You may want to cache slow operations (like internet lookups) to gain some speed,
but caching an operation that is already as fast as the cache lookup (i.e. the local NS lookup) does not make much sense.