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coredns/plugin/nsid/README.md
Miek Gieben 62317c3c14 update doc to not use the root zone for everything (#3288)
Update all documentation in the tree to use example.org as an example
configuration (in so far possible). As to get out of the just use "."
and fallthrough and things would be fine.

Signed-off-by: Miek Gieben <miek@miek.nl>
2019-09-19 06:17:53 -07:00

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# nsid
## Name
*nsid* - adds an identifier of this server to each reply.
## Description
This plugin implements [RFC 5001](https://tools.ietf.org/html/rfc5001) and adds an EDNS0 OPT
resource record to replies that uniquely identify the server. This is useful in anycast setups to
see which server was responsible for generating the reply and for debugging.
This plugin can only be used once per Server Block.
## Syntax
~~~ txt
nsid [DATA]
~~~
**DATA** is the string to use in the nsid record.
If **DATA** is not given, the host's name is used.
## Examples
Enable nsid:
~~~ corefile
example.org {
whoami
nsid Use The Force
}
~~~
And now a client with NSID support will see an OPT record with the NSID option:
~~~ sh
% dig +nsid @localhost a whoami.example.org
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46880
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 3
....
; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; NSID: 55 73 65 20 54 68 65 20 46 6f 72 63 65 ("Use The Force")
;; QUESTION SECTION:
;whoami.example.org. IN A
~~~
## Also See
[RFC 5001](https://tools.ietf.org/html/rfc5001)