Root servers list: the DNS root name servers and where they run

What the root servers do

ICANN defines a root server as "An authoritative name server that responds to queries about the contents of the root zone." The root zone is the list of every top-level domain and the name servers that run it; in ICANN's words, "The root zone contains all the information needed to find top-level domains." The edition in the root zone file on September 26, 2026 has serial 2026092601 and delegates 1,438 TLDs, from .aaa to .zw.

A root server does not store your domain. It answers a resolver with a referral: RFC 1034 describes a name server response that "either contains the answer to the question or a referral to other name servers". Ask a root server about www.example.com and it points to the 13 .com name servers, a.gtld-servers.net to m.gtld-servers.net; those in turn point to the servers of example.com. Resolvers keep these referrals, and the operators note: "For the DNS root, caching lasts up to 2 days." Their FAQ adds that "only a tiny fraction" of queries, typically less than 1% in the study it cites, needs a new contact with the root.

Every letter serves the same data. ICANN states: "All root servers are expected to have (and respond to queries about) the current edition of the root zone." RFC 7720 sets the service rules, for example that the root name service "MUST answer queries from any entity conforming to [RFC1122] with a valid IP address."

How many root server sites there are

The 13 root server identities are not 13 machines. The operators' FAQ puts it this way: "Each RSI operates at one IPv4 and one IPv6 address. (There are 13 RSIs and 12 RSOs because one RSO operates two RSIs.)" Behind each address sit many sites. On September 26, 2026 their lists held 1,572 operational sites with 2,028 instances. The headline on the operators' home page at 19:26 UTC that day read that "the root server system consists of 2045 operational instances operated by the 12 independent root server operators"; the per-letter lists on the same page add up to 2,028 instances at operational sites plus 17 at 15 L-root sites marked suspended, 2,045 in all. K-root also lists 16 decommissioned sites.

The spread is uneven. F-root has the most sites (386), then E (328) and D (231), while B and G have 6 each. 764 sites are global and 808 local. The FAQ explains the difference: "For global instances, the route advertisement is permitted to spread throughout the Internet", while "With a local instance, however, the route advertisement is limited to only nearby networks." It adds: "All operators provide service to the entire Internet through at least one global instance." 43 sites are listed as IPv4 only. The service as a whole must carry both protocols: RFC 7720 says the root name service "MUST support IPv4 [RFC791] and IPv6 [RFC2460] transport of DNS queries and responses", and every letter has an IPv6 address. As the FAQ puts it, "Different operators deploy a different number of instances."

Anycast: one address, many sites

All the sites of one letter share its IP address. ICANN's glossary describes what happens to a query: "When a resolver submits a query to a root server, anycast routing relays the query packet to the nearest (in terms of routing layout) root server instance." Failures are handled the same way: "If a local instance is unavailable (perhaps due to a power outage or a network problem), routers automatically redirect the query to the next nearest instance." The operators add that "Root server instances are generally located at data centers and exchange points."

F-root, for example, lists sites in both Tokyo and Toronto, so a query to f.root-servers.net from each city can reach a different machine behind the same address. The finder above lists every site from the operators' data, and the table below sums them by country.

The root hints file

A resolver needs the root server addresses before it can look up anything else. IANA notes that operators of recursive resolvers typically need to configure a root hints file, which "contains the names and IP addresses of the authoritative name servers for the root zone, so the software can bootstrap the DNS resolution process." InterNIC publishes it as named.root. The copy fetched on September 26, 2026 says it was last updated September 24, 2026, is tied to root zone version 2026092401, and lists the 13 names with a TTL of 3,600,000 seconds, about 42 days. You rarely need to edit it: IANA notes that "For many pieces of software, this list comes built into the software."

Comments in the file record the former host names of 9 letters: A was ns.internic.net, B was ns1.isi.edu, C was c.psi.net, D was terp.umd.edu, E was ns.nasa.gov, F was ns.isc.org, G was ns.nic.ddn.mil, H was aos.arl.army.mil and I was nic.nordu.net.

dig . NS @a.root-servers.net
dig com. NS @k.root-servers.net +norecurse
curl -O https://www.internic.net/domain/named.root

Sources and method

• IANA: Root Servers (letters, host names, IPv4 and IPv6 addresses, operators), fetched September 26, 2026.
• InterNIC root hints file named.root and root zone file (serial 2026092601), fetched September 26, 2026.
• root-servers.org, the site of the root server operators: per-letter site lists, summary counts and data file, fetched September 26, 2026; root-servers.org FAQ.
• ICANN glossary: root server, root server instance, root server operator, root zone.
• IANA: Root Files; RFC 7720 (root name service requirements); RFC 1034.
• Method: every count on this page is computed by script from the saved files. Sites and instances are those with status operational in the operators' lists; country names come from Unicode CLDR 47.0 and city names written in capitals are shown in title case.