A TLD name server is an authoritative DNS server for a top-level domain such as .com or .io. It holds the TLD zone and tells resolvers which name servers answer for each domain registered under it. The root zone delegates every TLD to its name servers with NS records and adds their IP addresses as glue. In the root zone file with serial 2026092501, the 1,438 TLDs use 5,912 different name server hosts, a median of 6 per TLD, and .com, .edu and .net have the most, 13 each.
Where TLD name servers sit in DNS
ICANN's glossary puts the root zone at the top of the DNS hierarchy and says: "The root zone contains all the information needed to find top-level domains." What it holds for each TLD is a delegation. To put one into effect, ICANN explains, "the operator of the parent domain must update its zone file to point to the authoritative name servers for the child domains". For a TLD, those authoritative servers are the TLD name servers.
They are run for the registry. ICANN's definition of a registry operator says it "operates the TLD's authoritative name servers and generates the zone file", and its entry for registry adds: "The Domain Name System consults the TLD registry to obtain the authoritative name servers for the domain names registered in that TLD." In practice a resolver looking up www.example.io asks a root server, which refers it to the .io name servers (a0.nic.io, a2.nic.io, b0.nic.io and c0.nic.io); those refer it to the servers of example.io. RFC 1034 describes that pattern: a name server response "either contains the answer to the question or a referral to other name servers".
TLD name server lookup
Look up the name servers and glue addresses of any TLD, or find every TLD served by a name server host. Data: the IANA root zone file, serial 2026092501.
How many name servers each TLD has
IANA's technical rules state: "There must be at least two NS records listed in a delegation, and the hosts must not resolve to the same IP address." RFC 1034 gives the reason for more than one: "A given zone will be available from several name servers to insure its availability in spite of host or communication link failure." Most TLDs go well beyond the minimum. The median is 6 and the average 5.26. .com, .edu and .net have 13 each; for .com they are a.gtld-servers.net through m.gtld-servers.net. 14 TLDs run on exactly 2, including .firmdale, .gy, .kp, .mh, .sl and .so.
| Name servers | TLDs | Share |
|---|---|---|
| 2 | 14 | 1.0% |
| 3 | 79 | 5.5% |
| 4 | 501 | 34.8% |
| 5 | 106 | 7.4% |
| 6 | 576 | 40.1% |
| 7 | 24 | 1.7% |
| 8 | 120 | 8.3% |
| 9 | 8 | 0.6% |
| 10 | 6 | 0.4% |
| 12 | 1 | 0.1% |
| 13 | 3 | 0.2% |
Glue, in-zone hosts and IPv6
ICANN defines a glue record this way: "A resource record in a zone file that provides the Internet Protocol (IP) address of an authoritative name server for a subdomain." The root zone file carries IPv4 glue for 5,910 of the 5,912 name server hosts and IPv6 glue for 5,633. 1,420 TLDs have at least one IPv6 glue address; 18 have none in the root zone, among them .cd, .ck, .dj, .et, .fk and .ge.
Many registries name their servers inside the TLD itself, like a0.nic.io for .io. 1,064 TLDs have at least one name server under their own name and 947 use only such hosts. The rest rely entirely on hosts under other extensions, as .com does with gtld-servers.net.
What IANA checks before a change
IANA lists the technical tests it runs on delegation changes, and notes: "This includes changes to the name server set (NS records) and any associated delegation signer (DS) records." Besides the two-server minimum, two rules stand out: "The name servers must answer DNS queries over both the UDP and TCP protocols on port 53." and "The name servers must be in at least two topologically separate networks." On the DNSSEC side, 1,351 of the 1,438 TLDs have a DS record in the root zone, the record RFC 4034 describes as one that "refers to a DNSKEY RR and is used in the DNS DNSKEY authentication process." The full signed list is on our TLDs with DNSSEC page.
dig NS io. @a.root-servers.net
dig NS com. +shortTLD name servers: frequently asked questions
What is a TLD name server?
What are the name servers for .com?
How many name servers does a TLD need?
What is the difference between a root server and a TLD name server?
How do I find the name servers of a TLD?
What is a glue record?
Sources and method
- IANA root zone file (InterNIC copy), serial 2026092501, fetched September 25, 2026 at 19:35 UTC: NS, glue A and AAAA, and DS records.
- IANA Root Zone Database: the name servers on every delegation record were cross-checked against the root zone file and match for all 1,438 TLDs.
- IANA technical requirements for authoritative name servers.
- ICANN glossary: root zone, delegation, registry operator, registry, glue record.
- RFC 1034 (DNS concepts) and RFC 4034 (DS record).
- Method: all counts are computed by script from the saved root zone file. A host counts as in-zone when its name ends in the TLD it serves.