One of the 13 root name servers

ISC operates the “F-Root” domain server, one of the 13 Internet root name servers known as A-Root through M-Root. We have operated F-Root for the Internet since 1994. The Root Server Technical Operations Association maintains a map that shows the location of all of the world’s root name servers. Over 230 of them are F-Root nodes.


If you are perplexed that the number of F-Root servers is greater than 13 (the number of root name servers), you can read about the “anycast” scheme used to make the servers collectively behave as one server. F-Root answers queries over IPv4 on, and over IPv6 on 2001:500:2f::f using a hierarchical anycast technique and BIND 9 software. Network operators can improve their access to the F-Root name server, and hence the reliability of the DNS in general, by peering with ISC at the exchange points where we maintain a presence.


We have almost 3,000 F-Root peers. For information about peering with ISC, see our peering information page.

Hosting F-Root

If you think your users would benefit from the improved DNS stability that a local F-Root Server would bring and are interested in hosting an F-Root node, please first read the Hosting an F-Root Node - Process Overview page and the technical requirements for hosting an F-Root node for more information.

If you are a researcher and your research involves F.root-servers.net in any way, please contact us at f-root@isc.org and we will be happy to provide you with first-hand information on any aspects of F-Root.

Our Commitment to F-Root

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


For a current list of F-Root nodes, see the Root Server Technical Operations Association website and select F-Root at the bottom of the page.

Which F-Root Node Am I Using?

To ensure that your users have access to an appropriate local root server it can be useful to find out which instance of the F-Root name server you are currently using. If there is a site listed close to you but you do not appear to be using it, ask your ISP to contact us so we can make the local site available to their customers.

To find out which F-Root site is answering your queries, try one or both of the following:

traceroute f.root-servers.net

The route your packets take to reach F should give you some information about which site you are using.

dig +norec @f.root-servers.net hostname.bind chaos txt

This command sends a query to the F-Root nameserver, asking it to reveal the name of the particular server which answers the query. The hostname will contain an IATA three letter airport code, allowing the location of the server to be identified. The dig utility is distributed with ISC BIND 9.

F-Root’s Data Collection Policy

ISC routinely captures all DNS traffic sent to F-root for analysis in the event of a network attack or to help diagnose network issues. This data is deleted after 10 days.

Once a year (or occasionally more often if significant changes are happening in the global DNS) a 2 to 3 day snapshot of anonymized F-Root traffic is sent to DNS-OARC for part of their “Day In the Life of the Internet” (DITL) survey. Our data is not shared elsewhere.

Research on the DNS root