Domain Name System (DNS)

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There are currently 13 root domain name servers, named a.root-servers.net through i.root-servers.net. Currently, NSI operates the "A" root server, which maintains the authoritative root database and replicates changes to the other root servers on a daily basis. Reason for 13 servers

"A current name server running on a 32-bit CPU serving the root, com, edu, gov, in-addr.arpa, mil, net and org currently weighs in at approximately 430MB. Most of the name servers we commonly refer to as "root name servers" carry a common set of zone files. The current sizes of the zone files commonly served by these "root name servers" are (sorted by increasing size):

Load of the root servers; more statistics and details

"[NSI] is installing multiple Sun Microsystems E-10000 and 4500 enterprise servers with the capacity to handle millions of simultaneous transactions. 'The amount of traffic that we are getting has required us to literally double the number of servers every six months,' said Dave Holtzman, senior vice president of engineering at Network Solutions. Holtzman said the company's Whois server, which holds the names and addresses of domain name owners, gets as many as 40 million hits a month, while the main domain root server gets as many as 3,000 hits a second." (NYT, May 7, 1999 )

The GTLD are on different servers:

; <<>> DiG 8.2 <<>> ns com. 
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 12, AUTHORITY: 0, ADDITIONAL: 12
;; QUERY SECTION:
;;      com, type = NS, class = IN

;; ANSWER SECTION:
com.                    4d18h29m6s IN NS  I.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  B.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  D.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  A.ROOT-SERVERS.NET.
com.                    4d18h29m6s IN NS  E.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  F.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  J.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  K.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  A.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  M.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  G.GTLD-SERVERS.NET.
com.                    4d18h29m6s IN NS  C.GTLD-SERVERS.NET.

;; ADDITIONAL SECTION:
I.GTLD-SERVERS.NET.     5d30m32s IN A   192.36.144.133
B.GTLD-SERVERS.NET.     4d15h51m32s IN A  203.181.106.5
D.GTLD-SERVERS.NET.     5d30m32s IN A   208.206.240.5
A.ROOT-SERVERS.NET.     5d30m32s IN A   198.41.0.4
E.GTLD-SERVERS.NET.     5d30m32s IN A   207.200.81.69
F.GTLD-SERVERS.NET.     5d30m32s IN A   198.17.208.67
J.GTLD-SERVERS.NET.     5d30m32s IN A   210.132.100.101
K.GTLD-SERVERS.NET.     5d30m32s IN A   213.177.194.5
A.GTLD-SERVERS.NET.     21h24m18s IN A  198.41.3.38
M.GTLD-SERVERS.NET.     5d30m32s IN A   202.153.114.101
G.GTLD-SERVERS.NET.     5d30m32s IN A   198.41.3.101
C.GTLD-SERVERS.NET.     5d30m32s IN A   205.188.185.18
mil 20KB
root-zone 90KB
gov 117KB
edu 880KB
in-addr.arpa 13MB
net 19MB
org 19MB
com 228MB
(Havard.Eidnes@runit.sintef.no, March 1, 1998)

Each top level domain also has one or more servers.

For Germany, these include:
193.196.32.1
192.76.144.66
137.39.1.3
128.63.5.4
192.5.25.5,
193.0.0.193
192.36.125.2
192.36.148.18
128.55.128.191
128.55.32.12

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Last updated by Henning Schulzrinne