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22c6e3e179
`upstream` is not needed as a setting; just set if unconditionally and remove all documentation and tests for it. At some point we want remove the hanlding for `upstream` as well and error out on seeing it. Signed-off-by: Miek Gieben <miek@miek.nl>
64 lines
1.6 KiB
Markdown
64 lines
1.6 KiB
Markdown
# secondary
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## Name
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*secondary* - enables serving a zone retrieved from a primary server.
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## Description
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With *secondary* you can transfer (via AXFR) a zone from another server. The retrieved zone is
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*not committed* to disk (a violation of the RFC). This means restarting CoreDNS will cause it to
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retrieve all secondary zones.
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~~~
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secondary [ZONES...]
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~~~
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* **ZONES** zones it should be authoritative for. If empty, the zones from the configuration block
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are used. Note that without a remote address to *get* the zone from, the above is not that useful.
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A working syntax would be:
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~~~
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secondary [zones...] {
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transfer from ADDRESS
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transfer to ADDRESS
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}
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~~~
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* `transfer from` specifies from which address to fetch the zone. It can be specified multiple times;
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if one does not work, another will be tried.
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* `transfer to` can be enabled to allow this secondary zone to be transferred again.
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When a zone is due to be refreshed (Refresh timer fires) a random jitter of 5 seconds is
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applied, before fetching. In the case of retry this will be 2 seconds. If there are any errors
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during the transfer the transfer fails; this will be logged.
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## Examples
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Transfer `example.org` from 10.0.1.1, and if that fails try 10.1.2.1.
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~~~ corefile
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example.org {
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secondary {
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transfer from 10.0.1.1
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transfer from 10.1.2.1
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}
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}
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~~~
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Or re-export the retrieved zone to other secondaries.
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~~~ corefile
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. {
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secondary example.net {
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transfer from 10.1.2.1
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transfer to *
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}
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}
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~~~
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## Bugs
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Only AXFR is supported and the retrieved zone is not committed to disk.
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