DNS

1. Overview
2. Scheduled Updates / Maintenance Windows
3. DNS Zone Push
4. DNS service
5. Name Servers
6. IP Connectivity
7. Glue Records

Overview

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 master name servers and seven slave name servers. The master name servers are updated with data from the SRS but are not themselves available for Internet queries. This function is performed by the slave name servers (known as ns1.dns.net.nz to ns7.dns.net.nz) which download their data from the masters.

Scheduled Updates / Maintenance Windows

Details of scheduled updates and maintenance windows for the DNS servers are available here.

DNS Zone Push

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

DNS service

To provide the DNS Resolution Service for the .nz domain name space. This includes the following:

• Ensuring that the .nz Name Service is always available, accessible and current;
• Receipt of domain name delegation and glue information from the SRS;
• Dissemination of .nz TLD and Second Level Domain (2LD) zone files, and management of the .nz Name Servers; and
• Dissemination of delegation and glue information concerning domain name in the .nz TLD and 2LD.

Note: To minimise the risk of single points of failure it is required to have geographical (both nationally and internationally) diversity and topological (Network) diversity. That the geographical and topological diversity requirement is designed with the possibility that some servers may cease to be available at any given time, in such situations that the routing will allow for continued access to the .nz domain name service.

Name Servers

The following table lists the seven .nz slave name servers along with the name of the company managing each server.

IP Connectivity

All the .nz name servers are capable of accepting requests and sending corresponding responses using IP version 4 (IPv4) transport. ns1.dns.net.nz, ns2.dns.net.nz and ns5.dns.net.nz are also capable of accepting requests and sending corresponding responses using IP version 6 (IPv6) transport. NS1 and NS2 are connected to the NZ IPv6 Internet Exchange

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)