ptaggr

Name

Plugin Ptaggr is able to aggregate PTR request answers of several upstream servers.

Description

The ptaggr plugin allows an extra set of upstreams be specified which will be used to serve an aggregated answer of all answers retrieved near those queried upstreams. The ptaggr plugin utilizes the forward plugin (https://coredns.io/plugins/forward) to query the specified upstreams.

The ptaggr plugin supports only DNS protocol and random policy w/o additional forward parameters, so following directives will fail:

. {
    forward . 8.8.8.8
    ptaggr . tls://192.168.1.1:853 {
        policy sequential
    }
}

As the name suggests, the purpose of the ptaggr is to allow several primary dns servers to give their own answer for a reverse request, you may need this when you have for example several subzones managed by several DNS authoritative servers that do not share any root in term of DNS tree.

Syntax

{
    ptaggr [original] [privateonly] . DNS_RESOLVERS
}

• original is optional flag. If it is set then ptaggr uses original request instead of potentially changed by other plugins
• privateonly is optional flag. If it is set then aggregation mechanism happen only for requested reverse IPv4 requests from RFC 1918 private ranges
• DNS_RESOLVERS accepts dns resolvers list. Requests will be forked near all those upstreams.

Building CoreDNS with ptaggr

When building CoreDNS with this plugin, ptaggr should be positioned before forward in /plugin.cfg.

Examples

Ptaggr aggregated reverse answer with 3 upstreams

The following specifies that all requests are forwarded to 8.8.8.8, 1.1.1.1 and 208.67.222.222.

. {
    forward in-addr.arpa 8.8.8.8
    ptaggr in-addr.arpa 1.1.1.1:53 208.67.222.222:53
    log
}