Root servers
The term root servers usually refers to the network of nameservers, operated by various entities across the globe, that are authoritative for the root zone published by IANA. The IP addresses of the root servers are hard-coded into the root hints file shipped with all DNS server implementations.
There are currently thirteen root servers, with names in the form letter.root-servers.net where letter ranges from A to M:
| Letter | Old name | Operator | Location |
|---|---|---|---|
| A | ns.internic.net | VeriSign | Dulles, Virginia |
| B | ns1.isi.edu | ISI | Marina del Rey, California |
| C | c.psi.net | Cogent Communications | distributed using anycast |
| D | terp.umd.edu | University of Maryland | College Park, Maryland |
| E | ns.nasa.gov | NASA | Mountain View, California, USA |
| F | ns.isc.org | ISC | distributed using anycast |
| G | ns.nic.ddn.mil | U.S. DoD NIC | Columbus, Ohio |
| H | aos.arl.army.mil | U.S. Army Research Lab | Aberdeen Proving Ground, Maryland, USA |
| I | nic.nordu.net | Autonomica | distributed using anycast |
| J | VeriSign | distributed using anycast | |
| K | RIPE NCC | distributed using anycast | |
| L | ICANN | Los Angeles, California | |
| M | WIDE Project | distributed using anycast |
Older servers had their own name before the policy of using similar names was established.
No more names can be used because of protocol limitations - UDP packet can only carry 512 bytes reliably and a hint file with more than 13 servers would be larger than 512 bytes - but the C, F, I, J, K and M servers now exist in multiple locations on different continents, using anycast announcements to provide a decentralized service. As a result most of the physical, rather than nominal, root servers are now outside the United States.
External Links
- Root Server Technical Operations Association
- Root servers on Wikipedia
- The AS112 Project, which seeks to mitigate the effects of broken DNS implementations on the root server networks
ICANNwiki: An industry resource fostering global collaboration and transparency within the ICANN community
