coredns/man/coredns-secondary.7

.\" generated with Ronn/v0.7.3
.\" http://github.com/rtomayko/ronn/tree/0.7.3
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.TH "COREDNS\-SECONDARY" "7" "January 2018" "CoreDNS" "CoreDNS plugins"
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.SH "NAME"
\fIsecondary\fR \- enables serving a zone retrieved from a primary server\.
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.SH "DESCRIPTION"
With \fIsecondary\fR you can transfer (via AXFR) a zone from another server\. The retrieved zone is \fInot committed\fR to disk (a violation of the RFC)\. This means restarting CoreDNS will cause it to retrieve all secondary zones\.
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.IP "" 4
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.nf

secondary [ZONES\.\.\.]
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.fi
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.IP "" 0
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.IP "\(bu" 4
\fBZONES\fR zones it should be authoritative for\. If empty, the zones from the configuration block are used\. Note that without a remote address to \fIget\fR the zone from, the above is not that useful\.
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.IP "" 0
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.P
A working syntax would be:
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.IP "" 4
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.nf

secondary [zones\.\.\.] {
    transfer from ADDRESS
    transfer to ADDRESS
    upstream ADDRESS\.\.\.
}
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.fi
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.IP "" 0
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.IP "\(bu" 4
\fBtransfer from\fR specifies from which address to fetch the zone\. It can be specified multiple times; if one does not work, another will be tried\.
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.IP "\(bu" 4
\fBtransfer to\fR can be enabled to allow this secondary zone to be transferred again\.
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.IP "\(bu" 4
\fBupstream\fR defines upstream resolvers to be used resolve external names found (think CNAMEs) pointing to external names\. This is only really useful when CoreDNS is configured as a proxy, for normal authoritative serving you don\'t need \fIor\fR want to use this\. \fBADDRESS\fR can be an IP address, and IP:port or a string pointing to a file that is structured as /etc/resolv\.conf\.
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.IP "" 0
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.P
When a zone is due to be refreshed (Refresh timer fires) a random jitter of 5 seconds is applied, before fetching\. In the case of retry this will be 2 seconds\. If there are any errors during the transfer the transfer fails; this will be logged\.
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.SH "EXAMPLES"
Transfer \fBexample\.org\fR from 10\.0\.1\.1, and if that fails try 10\.1\.2\.1\.
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.IP "" 4
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.nf

example\.org {
    secondary {
        transfer from 10\.0\.1\.1
        transfer from 10\.1\.2\.1
    }
}
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.fi
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.IP "" 0
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.P
Or re\-export the retrieved zone to other secondaries\.
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.IP "" 4
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.nf

\&\. {
    secondary example\.net {
        transfer from 10\.1\.2\.1
        transfer to *
    }
}
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.fi
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.IP "" 0
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.SH "BUGS"
Only AXFR is supported and the retrieved zone is not committed to disk\.