Network Administration: Root Servers - dummies

Network Administration: Root Servers

The core of Domain Naming Service (DNS) comprises the root servers, which are authoritative for the entire Internet. The main function of the root servers is to provide the address of the DNS servers that are responsible for each of the top-level domains. These servers, in turn, can provide the DNS server address for subdomains beneath the top-level domains.

The root servers are a major part of the glue that holds the Internet together. As you can imagine, they’re swamped with requests day and night. A total of 13 root servers are located throughout the world. The following table lists the IP address and location of each of the 13 root servers.

The 13 Root Servers
Server IP Address Operator Location
A 198.41.0.4 VeriSign Global Registry Services Dulles, VA
B 192.228.79.201 Information Sciences Institute Marina Del Rey, CA
C 192.33.4.12 Cogent Communications Herndon, VA and Los Angeles, CA
D 128.8.10.90 University of Maryland College Park, MD
E 192.203.230.10 NASA Ames Research Center Mountain View, CA
F 192.5.5.241 Internet Systems Consortium Palo Alto, CA; San Jose, CA; New York City; San Francisco;
Madrid; Hong Kong; Los Angeles
G 192.112.36.4 U.S. DOD Network Information Vienna, VA Center
H 128.63.2.53 U.S. Army Research Lab Aberdeen, MD
I 192.36.148.17 Autonomica Stockholm
J 192.58.128.30 VeriSign Global Registry Services Dulles, VA; Mountain View CA; Sterling, VA (two locations);
Seattle, WA; Amsterdam, NL; Atlanta, GA; Los Angeles
K 193.0.14.129 Reseaux IP Europeens Network London Coordination Centre
L 199.7.83.42 IANA Los Angeles
M 202.12.27.33 WIDE Project Tokyo

DNS servers learn how to reach the root servers by consulting a root hints file that’s located on the server. In the Unix/Linux world, this file is known as named.root and can be found at /etc/named.root. For Windows DNS servers, the file is called cache.dns and can be found in windowssystem32dns or winntsystem32dns, depending on the Windows version. The following listing shows the file itself.

The Named.Root File

;       This file holds the information on root name servers needed to
;       initialize cache of Internet domain name servers
;       (e.g. reference this file in the "cache  .  <file>"
;       configuration file of BIND domain name servers).
;
;       This file is made available by InterNIC 
;       under anonymous FTP as
;           file                /domain/named.root
;           on server           FTP.INTERNIC.NET
;       -OR-                    RS.INTERNIC.NET
;
;       last update:    Dec 12, 2008
;       related version of root zone:   2008121200
;
; formerly NS.INTERNIC.NET
;
.                        3600000  IN  NS    A.ROOT-SERVERS.NET.
A.ROOT-SERVERS.NET.      3600000      A     198.41.0.4
A.ROOT-SERVERS.NET.      3600000      AAAA  2001:503:BA3E::2:30
;
; FORMERLY NS1.ISI.EDU
;
.                        3600000      NS    B.ROOT-SERVERS.NET.
B.ROOT-SERVERS.NET.      3600000      A     192.228.79.201
;
; FORMERLY C.PSI.NET
;
.                        3600000      NS    C.ROOT-SERVERS.NET.
C.ROOT-SERVERS.NET.      3600000      A     192.33.4.12
;
; FORMERLY TERP.UMD.EDU
;
.                        3600000      NS    D.ROOT-SERVERS.NET.
D.ROOT-SERVERS.NET.      3600000      A     128.8.10.90
;
; FORMERLY NS.NASA.GOV
;
.                        3600000      NS    E.ROOT-SERVERS.NET.
E.ROOT-SERVERS.NET.      3600000      A     192.203.230.10
;
; FORMERLY NS.ISC.ORG
;
.                        3600000      NS    F.ROOT-SERVERS.NET.
F.ROOT-SERVERS.NET.      3600000      A     192.5.5.241
F.ROOT-SERVERS.NET.      3600000      AAAA  2001:500:2F::F
;
; FORMERLY NS.NIC.DDN.MIL
;
.                        3600000      NS    G.ROOT-SERVERS.NET.
G.ROOT-SERVERS.NET.      3600000      A     192.112.36.4
;
; FORMERLY AOS.ARL.ARMY.MIL
;
.                        3600000      NS    H.ROOT-SERVERS.NET.
H.ROOT-SERVERS.NET.      3600000      A     128.63.2.53
H.ROOT-SERVERS.NET.      3600000      AAAA  2001:500:1::803F:235
;
; FORMERLY NIC.NORDU.NET
;
.                        3600000      NS    I.ROOT-SERVERS.NET.
I.ROOT-SERVERS.NET.      3600000      A     192.36.148.17
;
; OPERATED BY VERISIGN, INC.
;
.                        3600000      NS    J.ROOT-SERVERS.NET.
J.ROOT-SERVERS.NET.      3600000      A     192.58.128.30
J.ROOT-SERVERS.NET.      3600000      AAAA  2001:503:C27::2:30
;
; OPERATED BY RIPE NCC
;
.                        3600000      NS    K.ROOT-SERVERS.NET.
K.ROOT-SERVERS.NET.      3600000      A     193.0.14.129 
K.ROOT-SERVERS.NET.      3600000      AAAA  2001:7FD::1
;
; OPERATED BY ICANN
;
.                        3600000      NS    L.ROOT-SERVERS.NET.
L.ROOT-SERVERS.NET.      3600000      A     199.7.83.42
L.ROOT-SERVERS.NET.      3600000      AAAA  2001:500:3::42   
;
; OPERATED BY WIDE
;
.                        3600000      NS    M.ROOT-SERVERS.NET.
M.ROOT-SERVERS.NET.      3600000      A     202.12.27.33
M.ROOT-SERVERS.NET.      3600000      AAAA  2001:DC3::35
; End of File