Filter AAAA App

A DNS App for Technitium DNS Server that filters AAAA responses when an A record also exists.

Overview

Post-processor – modifies responses after core resolution
AAAA filtering – returns NODATA when A records exist for the same name
Bypass support – skip local zones, networks, or domains

Integration / extension points

Implements: IDnsApplication, IDnsPostProcessor
Runs as a post-processor.

Configuration

dnsApp.config contains these keys:

Property	Type	Default	Description
`enableFilterAaaa`	boolean	`false`	Enables filtering.
`defaultTtl`	number	`30`	SOA TTL used for NODATA responses.
`bypassLocalZones`	boolean	`false`	Do not modify authoritative answers.
`bypassNetworks`	string[]	`[]`	Client networks excluded from filtering.
`bypassDomains`	string[]	`[]`	Domain names excluded from filtering.
`filterDomains`	string[]	`[]`	Domains eligible for filtering; empty means all domains.

Example

json

{
  "enableFilterAaaa": true,
  "defaultTtl": 30,
  "bypassLocalZones": false,
  "bypassNetworks": [],
  "bypassDomains": ["ipv6.example.com"],
  "filterDomains": []
}

Runtime behavior

Only acts on AAAA responses with NoError.
Skips signed responses when DNSSEC is in use.
Bypasses configured networks/domains and local zones when set.
If the same name has an A record, returns NODATA.

Risks / operational notes

Can break IPv6-only access if misconfigured.
Adds an extra A lookup per filtered query.
NODATA responses are cached negatively.