Test if a name server supports EDNS

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(New page: Use the following to test if a name server supports [http://en.wikipedia.org/wiki/EDNS EDNS], specifically EDNS0 in the examples below. When testing a name server, make sure to send a que...)
(dig +bufsize)
Line 14: Line 14:
'''; EDNS: version: 0, flags:; udp: 4096'''
'''; EDNS: version: 0, flags:; udp: 4096'''
-
=== dig +bufsize ===
+
== dig +bufsize ==
-
* According to '''dig'''(1), sending a non-zero '''bufsize''' causes an EDNS query to be sent.
 
* If your version of '''dig''' does not support '''+edns=#''', you will have to use '''+bufsize=B'''.
* If your version of '''dig''' does not support '''+edns=#''', you will have to use '''+bufsize=B'''.
 +
* According to '''dig'''(1), sending a non-zero '''bufsize''' causes an EDNS query to be sent.
$ '''dig @''nameserver'' +noall +comments +bufsize=1 ''query'''''
$ '''dig @''nameserver'' +noall +comments +bufsize=1 ''query'''''
;; Got answer:
;; Got answer:

Revision as of 20:10, 18 August 2008

Use the following to test if a name server supports EDNS, specifically EDNS0 in the examples below.

When testing a name server, make sure to send a query that will result in authoritative answer. For example, if ns.example.com is authoritative for example.com, send a query such as example.com soa. Sending a query for something like . ns to the name server will result in a timeout when specifying +edns=0.

dig +edns

  • If your version of dig supports +edns=#, use the following:
$ dig @nameserver +noall +comments +edns=0 query
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26316
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 9, ADDITIONAL: 10

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096

dig +bufsize

  • If your version of dig does not support +edns=#, you will have to use +bufsize=B.
  • According to dig(1), sending a non-zero bufsize causes an EDNS query to be sent.
$ dig @nameserver +noall +comments +bufsize=1 query
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61334
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 9, ADDITIONAL: 10

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
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