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List:       namedroppers
Subject:    Name Server Logic
From:       "john.p.mcnicholas" <john.p.mcnicholas () AWO ! COM>
Date:       1996-03-23 3:57:54
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Does everyone agree with my description of a name server's logic?  This name
server happens to be equipped with 4.9.3 and the noforwarders command.

A name server performs the following sequence of events in order to reply to a
query...

1)  check all local A (address) records
 a)  if found, then reply with answer (record found)
     - end query
 b)  if not found then go to step 2

2)  compare query to list of domains indicated by noforward command
 a)  if a match then go to step 3
 b)  if no match then send a recursive query to the address(es)
     listed in the forwarders command
  i)  if the forwarder responds with an answer (record
      found or record not found), then reply accordingly
      - end query
  ii)  if the forwarder does not respond within time
       limit, then go to step 3

3)  check all local NS (name server) records for the name server
    responsible for this domain
 a) if a match found then forward query to that name server
  i) if that name server responds with an answer (record
     found or record not found), then reply accordingly
     - end query
  ii) if that name server does not respond within time
      limit, then go to step 4
 b) if no match found then go to step 4

4)  forward query to root name server(s)
 a) if root responds with answer (record found or record not
    found) then reply accordingly - end query
 b) if root does not respond within time limit then end query

Thanks,
John

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