DNS

Overview

The domain name system or domain name server (DNS) is a system that stores and associates many types of information with domain names. Its most important function is to translate domain names into IP addresses, allowing computers that host domains to be contacted on the Internet. It also identifies the mail exchange servers that accept email for domains. The DNS provides a worldwide redirection service that is an essential component of contemporary Internet use and without which the World Wide Web would not be possible.

The domain name space is organised as a tree of domain names with collections of related nodes referred to as zones. Each zone is served by an authoritative DNS name server. To provide resilience in the event of computer failure, multiple DNS servers provide coverage of each domain. Thirteen root servers exist worldwide and DNS programs and operating systems have the IP addresses of these servers built in. However, because many root servers actually implement anycast, where many different computers can share the same IP address to deliver a single service over a large geographic region, the total number of physical name servers for the root zone is much larger and widely dispersed throughout the world.

NZRS operates the authoritative name servers for the second-level domains (2LDs) under .nz, such as .co.nz, .org.nz, etc. The .nz DNS consists of two primary name servers and seven secondary name servers. The primary name servers are updated with data from the SRS but are not themselves available for Internet queries. This function is performed by the secondary name servers (known as ns1.dns.net.nz to ns7.dns.net.nz) which download their data from the primaries.

DNS Zone Push

The DNS Zone push from SRS to the .nz secondary name servers occurs every hour on the hour.

DNS service

The availability target for the DNS service is 100% available, accessible and current;
Receipt of domain name delegation and glue information from the SRS.
Dissemination of .nz TLD zone files, and management of the .nz zone servers.
Dissemination of delegation and glue information concerning domain name in the .nz TLD.

Note: To minimise the risk of single points of failure there is geographical (both nationally and internationally) diversity and topological (Network) diversity

Name Servers

The following table lists the seven .nz secondary name servers along with the name of the company managing each server and its physical location.

Nameserver	Support	Location
ns1.dns.net.nz	NZRS	Wellington
ns2.dns.net.nz	NZRS	Albany
ns3.dns.net.nz	NZRS	Avalon
ns4.dns.net.nz	TelstraClear	Albany
ns5.dns.net.nz	UltraDNS	Multiple International
ns6.dns.net.nz	UltraDNS	Multiple International
ns7.dns.net.nz	Telecom	Auckland

Glue Records

The SRS accepts authoritative name server delegation details for domains and these details are published in the authoritative name servers for the .nz zones. Registrars are allowed to specify up to 10 name servers. Each name server must contain information for a fully qualified domain name field (FQDN). There is no requirement that any name servers are within the domain for which they are authoritative.

Registrars may also provide details of the IP addresses (IPv4 and/or IPv6) for the name servers, these details are also known as “Glue Records”. “Glue Records” are only required if the name server is “self-serving”. I.e. Glue records are needed when the authoritative name server for a domain is within the domain itself.

If registrars provide IPv6 addresses, there MUST be an IPv4 address provided, not just an IPv6 address. We recommend that domains are still accessible via IPv4 name servers.

The full technical details supporting IPv4 and IPv6 Glue records are available here....(pdf)


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