which Name sever is selected?

Barry Margolin barmar at alum.mit.edu
Fri Feb 28 16:06:26 UTC 2014


In article <mailman.2368.1393596895.20661.bind-users at lists.isc.org>,
 houguanghua <houguanghua at hotmail.com> wrote:

> If there is a list of NS records, the local name server uses the RTT (round 
> trip time) algorithm to find the fatest, and queries that server. 
> But I found it's not right. In the testing, the local name server doesn't 
> query the fastest authority name server. Some one tells me that if the local 
> name server gets the RTT to one remote server is les than 30ms, it will not 
> test RTT to other remote servers, even if the RTT is more less. In other 
> words, the local server will only query the first remote server with the RTT 
> less than 30ms. Who would tell me the truth? Thanks! Guanghua 		 	   		  

I believe the RTT values are grouped into ranges, and it prefers servers 
that are in a better range. 30 ms might be in the lowest range, so 
another server can't be better.

-- 
Barry Margolin
Arlington, MA


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