ISC operates the "F" root domain server, one of the 13 Internetroot name servers known as A-root through M-root. We have operated F-Root forIANA since 1994.

The Root Server Technical Operations Association maintains amap that shows the location of all of the world's root name servers. 46 of them are F Roots, operated by ISC. If you are perplexed that 46 (the number of F-root servers) is greater than 13 (the number of root name servers), you canread about the "anycast" scheme used to make the 46 servers collectively behave as 1 server.

F-root answers queries over IPv4 on 192.5.5.241, and over IPv6 on 2001:500:2f::f using ahierarchical anycast technique andBIND 9 software.

Network operators can improve their access to the F Root Nameserver, and hence the reliability of the DNS in general, by peering with ISC at the exchange points where we maintain a presence. For information about peering with ISC, see ourPeering Information Page.

On January 4th, 2008, ISC became the first root server operator to sign aMutual Responsibilities Agreement with ICANN, which identifies mutual responsibilities and is another step to enhance Internet stability.

ReadOct 2002 report detailing a denial-of-service attack on the root servers.

ReadMay 2009 news article about DE-CIX sponsoring anycast F-root in Frankfurt.

Below is a map showing the locations of F-root nodes worldwide.Here is a list of their locations, andhere are instructions for finding out which F-root is providing service to you.