The Root Servers are the ultimate backbone of the DNS system.

Every DNS server has a cache of addresses it's looked up recently (and some DNS resolvers - ie the local DNS client on your machine - have caches as well). But if you request a DNS name lookup that no local DNS server has tried to resolve, it has to speak to the Root Servers.

The Root Servers have very unimaginative names. They are up to However, there's actually more than 13 of them. Most of the Root Servers are present on the Internet using Anycast. This means that there are multiple machines on the network that have the same IP address, each one broadcasting its presence. When you try to hit that IP address, you'll automatically get the nearest one. This provides a significant amount of load balancing and protection against DDoS attacks. (This is the same system used by the DALnet IX project.)

The current Root Servers are as follows. Each entry has 4 lines - the server name, the operator, the location(s) of the server, and the IP address(es). This information is taken from and this is where you should pull your information for named.cache or equivalent files.

  • VeriSign Global Registry Services
  • Dulles VA
  • Information Sciences Institute
  • Marina Del Rey CA
  • (IPv4), 2001:478:65::53 (IPv6)
  • Cogent Communications
  • Herndon VA; Los Angeles; New York City; Chicago
  • NASA Ames Research Center
  • Mountain View CA
  • Internet Systems Consortium, Inc.
  • Ottawa; Palo Alto; San Jose CA; New York City; San Francisco; Madrid; Hong Kong; Los Angeles; Rome; Auckland; Sao Paulo; Beijing; Seoul; Moscow; Taipei; Dubai; Paris; Singapore; Brisbane; Toronto; Monterrey; Lisbon; Johannesburg; Tel Aviv; Jakarta; Munich; Osaka; Prague; Amsterdam
  • (IPv4), 2001:500::1035 (IPv6)
  • U.S. DOD Network Information Center
  • Vienna VA
  • U.S. Army Research Lab
  • Aberdeen MD
  • (IPv4), 2001:500:1::803f:235 (IPv6)
  • Autonomica/NORDUnet
  • Stockholm; Helsinki; Milan; London; Geneva; Amsterdam; Oslo; Bangkok; Hong Kong; Brussels; Frankfurt; Ankara; Bucharest; Chicago; Washington DC; Tokyo; Kuala Lumpur; Palo Alto; Jakarta; Wellington; Johannesburg; Perth; San Francisco; New York; Singapore; Miami; Ashburn (US)
  • VeriSign Global Registry Services
  • Dulles VA (2 locations); Mountain View CA; Seattle WA; Amsterdam; Atlanta GA; Los Angeles CA; Miami; Stockholm; London; Tokyo; Seoul; Singapore; Sterling VA (2 locations, standby)
  • Reseaux IP Europeens - Network Coordination Centre
  • London (UK); Amsterdam (NL); Frankfurt (DE); Athens (GR); Doha (QA); Milan (IT); Reykjavik (IS); Helsinki (FI); Geneva (CH); Poznan (PL); Budapest (HU); Abu Dhabi (AE); Tokyo (JP)
  • (IPv4), 2001:7fd::1 (IPv6)
  • WIDE Project
  • Tokyo; Seoul (KR); Paris (FR)
  • (IPv4), 2001:dc3::35 (IPv6)

Every DNS server needs to know the addresses of these Root Servers, so a file called "named.cache", "" or "root.hints" is often used to "prime" the server on startup. Technically this file should be kept up to date, but this isn't often necessary as the IP addresses of the root servers will usually stay the same even if the locations change (using Anycast).

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