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The UT System Office of Telecommunication Services (OTS) will provide secondary DNS name service to THEnet subscribers and UT System Network (UTSN) members when requested.

OTS provides DNS name service on a name server located in Austin. The service will soon expand to use name servers geographically distributed to three Texas cities: Austin, Dallas, and San Antonio.

Multiple Authoritative Name Servers

Each DNS domain must be served by at least two DNS servers although more than two is perfectly acceptable and sometimes recommended. Multiple authoritative name servers are required for each domain in order to provide continuity of DNS service in case any one server fails or becomes unreachable. One of name servers is designated as the primary master name server and the others are designated as secondary slave name servers. Each secondary name server periodically updates its zone data from the primary name server.

Geographic Distribution of Secondary DNS Name Servers

An additional strategy to ensure the availability of DNS service, is to distribute secondary name servers to geographically remote locations. In the event of a local power outage, a downed circuit, or any other connectivity failure, an unaffected remote name server can continue to serve DNS information about the local domain.

Requesting Secondary DNS Name Service

Secondary DNS name service should be requested both for the "forward" mapping (name to IP address) domain and for the "reverse" mapping (IP address to name) in-addr.arpa domain.

1. If necessary, complete the steps following prior to requesting name service:

A. Register your domain name(s) with the appropriate authority

You are responsible for registering your domain name(s) with the appropriate registration authority, even if UT System OTS is the registration authority. OTS will provide secondary name service for most domains directly related to an official organizational activity, excluding commercial activities operated by auxiliary enterprises (most .com domains). Visit Domain Registration Authorities for a list of domains commonly used on THEnet and their registrars.

B. Configure your primary name server

Primary DNS name service for each domain must be configured by the THEnet subscriber or UTSN member (primary name servers typically are located at the member site).

Note: Under limited circumstances, OTS can provide primary DNS name service for a member. This can be done only in the case of a very small DNS domain (no more than 10 records in the zone file), where the DNS data is expected to be static and will not change. Contact registrar@the.net for details.

SOA record timer fields: When configuring your primary name server for domains to be secondaried, OTS recommends the following SOA record timer field values: a refresh value of 10800 seconds (3 hours), a retry value of 3600 seconds (1 hour), an expire value of 1209600 seconds (2 weeks), a negative caching TTL (Time To Live) value of 10800 seconds (3 hours). Other choices may be reasonable.

SOA serial number field: Each SOA record has a serial number field, which must be incremented each time any update is done to the zone. A ten-digit serial number YYYYMMDDNN is recommended, where YYYYMMDD identifies the date of the latest update and NN specifies the version number of the update.

C. Configure DNS Server Security and Firewall Security

You need to configure any applicable firewall to permit DNS-required ports. The DNS uses UDP port 53 and TCP port 53 to serve requests. These two ports must be available for DNS queries to work correctly and may need to be explicitly permitted in the subscriber's firewall configuration. DNS zone transfers from a subscriber's primary name server can be limited to requests from selected IP addresses (including the IP addresses of OTS secondary DNS name servers).

However, zone transfer restrictions should be implemented only after OTS secondary name service has been configured and an acknowledgement has been received identifying the IP address of each OTS secondary name server.

2. Complete and submit the form to request secondary name service.

To request DNS secondary name service, THEnet subscribers and UTSN members should complete and submit the form:

3. Update domain registration

After secondary name service has been configured and OTS has indicated to the requestor that secondary name service is operational, THEnet subscribers and UTSN members must update each domain's registration to reflect the name and IP address of the OTS secondary name server. OTS will share the name server information once the service is operational.

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