Root servers – FAQs

  1. What is a root name server?
  2. What do root servers do?
  3. Who operates these root servers?
  4. Why there are only 13 root servers?
  5. Will new root server “letters” be allocated?
  6. What is “BGP Anycast”?
  7. Does BGP Anycast work well?
  8. Is there a difference between the different “letters”?
  9. Are “anycast” servers different from the “real” servers?
  10. Will APNIC become a “Root Server Operator”?
  11. Which root servers are APNIC deploying in the Asia Pacific?
  12. Why is APNIC involved?
  13. How APNIC can support deployment of root servers?
  14. Where are root servers being deployed in the Asia Pacific?

What is a root name server?

A root server or root name server is part of the Domain Name System (DNS), a worldwide distributed system that translates domain names into the IP addresses. The DNS is an important part of critical Internet infrastructure because it is used by almost all Internet applications to date.

What do root servers do?

Root servers are based in various locations around the world and publish the root zone file to other DNS servers and clients on the Internet. The root zone file describes where the authoritative servers for the DNS top-level domains (TLD) are located and how to reach them. This is the Internet’s equivalent of a phone book. They maintain a directory of domain names and translate them to IP addresses. This is necessary because, although domain names are easy for people to remember, computers or machines access websites based on numbers, that is, IP addresses.

Having root servers available closer to Internet users has an immediate impact on the speed of DNS services and each new deployment provides greater stability and resilience to the Internet.

Who operates these root servers?

There are 13 original root servers. A complete list of organizations that manage them and their respective IPv4/IPv6 addresses is available.

Why there are only 13 root servers?

At the time the DNS was designed, the IP address in use was IPv4, which contains 32 bits. For efficient networking and better performance, these IP addresses should fit into a single packet (using UDP, the DNS’s default protocol). Using IPv4, the DNS data that can fit into a single packet is limited to 512 bytes. As each IPv4 address requires 32 bytes, having 13 servers uses 416 bytes, leaving up to 96 bytes for the remaining protocol information.

As an IPv6 address is not limited by these constraints, it is possible new root servers may be established in the future.

Will new root server “letters” be allocated?

No. Rather than requiring new root server identifiers (such as A,B,C,…M), the BGP anycast technique will allow the existing root servers to be copied across multiple separate servers located at different points on the Internet.

What is “BGP Anycast”?

BGP Anycast is a technique to announce the same destination IP address range simultaneously from multiple places on the Internet. Within the BGP routing system, multiple routes to the same address space will be seen, and the topologically nearest route is given preference. Anycast can provide a fall over mechanism to DSN service, allows users to reach a topologically nearest DNS server and this reduces latency, and can provide resilience against DDoS attack.

Does BGP Anycast work well?

BGP Anycast is well tested and has been in use for many years in appropriate services such as the DNS. It is suitable for transaction-oriented services, such as the DNS or whois, but not for connection-oriented services, which require a long-term connection between a client and a particular server.

For more information, see:

  • RIPE-268, “Distributing K-Root Service by Anycast Routing of 193.0.14.129”
  • ISC’s Technical Note 2003-1,” Hierarchical Anycast for Global Service Distribution”

Is there a difference between the different “letters”?

There are differences between servers in terms of hardware, software, and operational practices; however, there is no hierarchy of status or importance among the servers. Each of the 13 separate root servers (that is, from A-Root to M-Root) behave identically in DNS terms and are distinguished only by their different “letter” names and IP addresses.

Are “anycast” servers different from the “real” servers?

No. When anycast distribution of an existing server is implemented, all servers become ‘anycast servers’, including the ‘original’ server. All anycast instances behave identically and have the same status within the DNS.

Will APNIC become a “Root Server Operator”?

No. The existing root server operators will maintain full and exclusive administrative control over all copies of their servers. APNIC’s contribution is to locate suitable hosts, and provide the equipment, if required.

Which root servers are APNIC deploying in the Asia Pacific?

APNIC has formal MoU agreements with the operators of the F-Root, the I-Root, K-Root, L-Root and is also cooperating actively with others too.

Why is APNIC involved?

While APNIC is not involved in domain name registrations, the DNS carries several critical Internet infrastructure services, including reverse DNS trees, in-addr.arpa and ip6.arpa. We have been asked many times to take some involvement in root server operations to improve access to these infrastructures for ISPs in the Asia Pacific region.

APNIC’s role in root server operations is as a voluntary facilitator and coordinator of root server deployments in this region to build the Internet infrastructure closer to its users.

How APNIC can support deployment of root servers?

In order to support to improve Internet infrastructure in the AP region, APNIC will provide to support to procure root server equipment to an organisation that is willing to deploy a root server for their community’s benefit by directly working with a relevant root server operator. Please see details of APNIC Memorandum of Understanding document for Root Server Equipment Procurement.

If you are interested in inquiring how you and APNIC can work together on a root server deployment, please send your inquiry to helpdesk@apnic.net.

Where are root servers being deployed in the Asia Pacific?

A number of anycast root servers are already deployed in the Asia Pacific region and are growing. You can find an updated list here.