dns concept

Someone in outside world looks up abc1234.com. His DNS server looks up the servers for .com. These are known. (Look in yoursrv-named-db-db.cache file if it is where I keep mine.) It looks something like this:

;; ANSWER SECTION: . 518400 IN NS M.ROOT-SERVERS.NET. . 518400 IN NS I.ROOT-SERVERS.NET. . 518400 IN NS E.ROOT-SERVERS.NET. . 518400 IN NS D.ROOT-SERVERS.NET. . 518400 IN NS A.ROOT-SERVERS.NET. . 518400 IN NS H.ROOT-SERVERS.NET. . 518400 IN NS C.ROOT-SERVERS.NET. . 518400 IN NS G.ROOT-SERVERS.NET. . 518400 IN NS F.ROOT-SERVERS.NET. . 518400 IN NS B.ROOT-SERVERS.NET. . 518400 IN NS J.ROOT-SERVERS.NET. . 518400 IN NS K.ROOT-SERVERS.NET. . 518400 IN NS L.ROOT-SERVERS.NET.

;; ADDITIONAL SECTION: M.ROOT-SERVERS.NET. 3600000 IN A 202.12.27.33 I.ROOT-SERVERS.NET. 3600000 IN A 192.36.148.17 E.ROOT-SERVERS.NET. 3600000 IN A 192.203.230.10 D.ROOT-SERVERS.NET. 3600000 IN A 128.8.10.90 A.ROOT-SERVERS.NET. 3600000 IN A 198.41.0.4 H.ROOT-SERVERS.NET. 3600000 IN A 128.63.2.53 C.ROOT-SERVERS.NET. 3600000 IN A 192.33.4.12 G.ROOT-SERVERS.NET. 3600000 IN A 192.112.36.4 F.ROOT-SERVERS.NET. 3600000 IN A 192.5.5.241 B.ROOT-SERVERS.NET. 3600000 IN A 192.228.79.201 J.ROOT-SERVERS.NET. 3600000 IN A 192.58.128.30 K.ROOT-SERVERS.NET. 3600000 IN A 193.0.14.129 L.ROOT-SERVERS.NET. 3600000 IN A 198.32.64.12

Any of these known servers will know where a .com server is, and will return the IP address of a .com server. His DNS server will then look up abc1234.com on that server and it should return the IP address desired.

Chances are very good that his DNS server will already know a .com server if it has recently looked up anything else in .com, so the average request does not even go to one of the root servers in the above list.

-- .~. Jean-David Beyer Registered Linux User 85642. V PGP-Key: 9A2FC99A Registered Machine 241939. ^^-^^ 06:45:01 up 23 days, 9:35, 3 users, load average: 4.25, 4.20, 4.07