[Dnsmasq-discuss] DHCPv6 hostname resolving

Quintus quintus at quintilianus.eu
Thu Apr 3 15:47:04 UTC 2014


Hi Simon,

Am 02.04.2014 20:34, schrieb Simon Kelley:
> Please could you do the following?
>
> 1) Check the dnsmasq leases file (normally
> /var/lib/misc/dnsmasq.leases) to see if the name "atlantis" appears in
> the relevant DHCPv6 lease?

It only appears for DHCPv4 leases, but not DHCPv6 ones. Here’s the full
contents of the lease file: http://pastie.org/8991576

> 2) See if the plain name (not FQDN) resolves
>
>  dig atlantis AAAA

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis AAAA
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13397
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.			IN	AAAA

;; Query time: 1 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:31:02 2014
;; MSG SIZE  rcvd: 26
-----------------------------------------

> 3) See if atlantis.internal.xxx.eu resolves.
>
>  dig atlantis.internal.xxx.eu AAAA

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.internal.xxx.eu AAAA
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 55319
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.internal.xxx.eu. IN AAAA

;; AUTHORITY SECTION:
xxx.eu.	2560	IN	SOA	ns.yyy.de. hostmaster.xxx.eu. 1391783412 16384 2048
1048576 2560

;; Query time: 56 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:35:04 2014
;; MSG SIZE  rcvd: 124
-----------------------------------------

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.cable.internal.xxx.eu AAAA
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33135
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4000
;; QUESTION SECTION:
;atlantis.cable.internal.xxx.eu.	IN AAAA

;; Query time: 100 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:31:22 2014
;; MSG SIZE  rcvd: 75
-----------------------------------------

Normal A records resolve just fine.

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31147
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.			IN	A

;; ANSWER SECTION:
atlantis.		0	IN	A	10.37.59.42

;; Query time: 9 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:30:55 2014
;; MSG SIZE  rcvd: 42
-----------------------------------------

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.cable.internal.xxx.eu A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10528
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.cable.internal.xxx.eu.	IN A

;; ANSWER SECTION:
atlantis.cable.internal.xxx.eu.	0 IN A 10.37.59.42

;; Query time: 1 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:31:15 2014
;; MSG SIZE  rcvd: 80
-----------------------------------------

This one (of course) does not:

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.internal.xxx.eu A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 27999
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.internal.xxx.eu. IN A

;; AUTHORITY SECTION:
xxx.eu.	2389	IN	SOA	ns.yyy.de. hostmaster.xxx.eu. 1391783412 16384 2048
1048576 2560

;; Query time: 35 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:37:54 2014
;; MSG SIZE  rcvd: 124
-----------------------------------------

I have however discovered a strange thing. If I send the same queries
from another computer (which is in the same subnet and domain), dnsmasq
doesn’t resolve the unqualified name:

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> altantis A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34618
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;altantis.			IN	A

;; Query time: 1 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:39:40 2014
;; MSG SIZE  rcvd: 26
-----------------------------------------

The FQDN is OK:

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.cable.internal.xxx.eu A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6200
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.cable.internal.xxx.eu.	IN A

;; ANSWER SECTION:
atlantis.cable.internal.xxx.eu.	0 IN A 10.37.59.42

;; Query time: 1 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:39:53 2014
;; MSG SIZE  rcvd: 80
-----------------------------------------

And this one errors as expected:

-----------------------------------------
; <<>> DiG 9.9.2-P2 <<>> atlantis.internal.xxx.eu A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 54270
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;atlantis.internal.xxx.eu. IN A

;; Query time: 1 msec
;; SERVER: 10.37.59.2#53(10.37.59.2)
;; WHEN: Thu Apr  3 17:40:06 2014
;; MSG SIZE  rcvd: 58
-----------------------------------------

AAAA records are never resolved.

> Cheers,
>
> Simon.

Vale,
Quintus

-- 
Blog: http://www.quintilianus.eu

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