DNS Stub Zone

A stub zone in zWAN CPE can be configured to point to an authoritative server for references to a specific zone. This can be a local or external DNS server that is directly reachable from the zWAN CPE. A stub zone is a copy of a zone that contains only the resource records necessary to identify the authoritative Domain Name System (DNS) servers for that zone. Stub zones help resolve names between separate DNS namespaces, which can be useful in scenarios such as corporate mergers or when integrating with an existing DNS server in an organization.

A stub zone consists of:

• The start of authority (SOA) resource record, name server (NS) resource records, and the glue A resource records for the delegated zone.
• The IP address of one or more master servers that update the stub zone. These servers are authoritative for the child zone and usually host the primary zone for the delegated domain name.

The stub zone maintains only the necessary information to contact the authoritative DNS servers, including NS records and A records required for resolution.

Differences Between Forward Zone, Auth Zone, and Stub Zone

• Stub Zone: Directs queries to an authoritative server to fetch information.
• Forward Zone: Sends queries to a recursive server to fetch information.
• Auth Zone: Loads a zone from a file and serves it locally or fetches information like an upstream server.

Process Overview

When a DNS client queries a DNS server hosting a stub zone, the server uses the stub zone’s resource records to resolve the query. The DNS server queries the authoritative DNS servers specified in the stub zone’s NS records. If these servers are unreachable, the DNS server attempts standard recursion using its root hints.

Functionality

Stub zones can be configured in zWAN CPE using the Add Stub Zone functionality. Each stub zone must have a unique name, and multiple stub zones can be configured.

Parameters

• serverInfo: IP/Hostname/Port of the authoritative server.
• stubFirst: (Default: Disabled) If enabled, retries without the stub clause if the query fails.
• stubPrime: (Default: Disabled) Performs NS set priming, similar to root hints.
• stubNoCache: (Default: Disabled) Prevents caching of stub zone data.
• stubTLSUpstream: (Default: Disabled) Enables TLS for stub queries.

Stub Zone Configuration

Add Stub Zone

Configures the CPE to refer to an authoritative DNS server for a specific zone.

Edit Stub Zone

Allows modification of stub zone parameters or temporary disabling of a stub zone.

Delete Stub Zone

Removes one or multiple configured stub zones.

List Stub Zones

Displays all configured stub zones with search and sorting functionality.

References

• Arch Linux Unbound Wiki
• Easy365Manager Stub Zone Guide