[Dnsmasq-discuss] Does dnsmasq support cname within same domain?

Wed Mar 2 22:13:38 UTC 2022

From: Dnsmasq-discuss <dnsmasq-discuss-bounces at lists.thekelleys.org.uk> On Behalf Of Frank Liu
Sent: Wednesday, March 2, 2022 12:46 PM
To: Matus UHLAR - fantomas <uhlar at fantomas.sk>; dnsmasq-discuss at lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] Does dnsmasq support cname within same domain?

On Wed, Mar 2, 2022 at 7:14 AM Matus UHLAR - fantomas via Dnsmasq-discuss <mailto:dnsmasq-discuss at lists.thekelleys.org.uk> wrote:
>> > > On Tue, Mar 01, 2022 at 01:01:51AM -0800, Frank Liu wrote:
>> > > > I am running dnsmasq for dhcp/dns of a local test domain: http://test.example.com.
>> > > > Everything works fine. When a dhcp client (eg: client1) comes up, it gets
>> > > > the IP from dnsmasq, and I can dig/nslookup http://client1.test.example.com to get
>> > > > its IP.
>> > > >
>> > > > When I add a cname in the same domain, eg:
>> > > > cname=http://alias.test.example.com,http://client1.test.example.com
>> > > >
>> > > > dig/nslookup of http://alias.test.example.com only returns name
>> > > > http://client1.test.example.com, not the actual IP of http://client1.test.example.com
>> > > >
>> > > > It's interesting that if I add the cname for a different domain, eg:
>> > > > cname=http://alias.dummy.example.com,http://client1.test.example.com
>> > > >
>> > > > dig/nslookup of http://alias.dummy.example.com will return both name
>> > > > http://client1.test.example.com and its IP.
>> > > >
>> > > > I tried a few different versions but that doesn't make a difference.

>> > On Tue, Mar 1, 2022 at 3:37 AM Geert Stappers via Dnsmasq-discuss wrote:
>> > > Please name those different versions.

>> On Tue, Mar 01, 2022 at 09:21:58AM -0800, Frank Liu wrote:
>> > 2.76 (Debian 9),   2.85 (Debian 11).

>On Tue, Mar 1, 2022 at 2:39 PM Geert Stappers via Dnsmasq-discuss 
> <mailto:dnsmasq-discuss at lists.thekelleys.org.uk> wrote:
>> Ah, I'm now beyond the ambiguty of different version of dig/nslookup.

On 02.03.22 01:28, Frank Liu wrote:
>I don't think it matters with test OS or test application.

it may matter, 

>I also tried:
>ping http://alias.dummy.example.com works, but ping http://alias.test.example.com gives
>unknown host error.
>(even though both names cname to the same http://client1.test.example.com in
>dnsmasq).

What do there result in?

dig http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com
dig -t any http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com

In below test, dnsmasq server (192.168.0.253) runs dnsmasq 2.85 (from Debian11).
I have below in the dnsmasq conf:

cname=http://alias.test.example.com,http://client1.test.example.com
cname=http://alias.dummy.example.com,http://client1.test.example.com

Test client is another Debian11 box

$ dig -v
DiG 9.16.22-Debian

$ dig @http://192.168.0.253 http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com

; <<>> DiG 9.16.22-Debian <<>> @http://192.168.0.253 http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29718
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://alias.dummy.example.com. IN A

;; ANSWER SECTION:
http://alias.dummy.example.com. 0 IN CNAME http://client1.test.example.com.
http://client1.test.example.com. 0 IN A 192.168.0.70

;; Query time: 20 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:27 UTC 2022
;; MSG SIZE  rcvd: 114

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62870
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://alias.test.example.com. IN A

;; ANSWER SECTION:
http://alias.test.example.com. 5 IN CNAME http://client1.test.example.com.

;; Query time: 20 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:27 UTC 2022
;; MSG SIZE  rcvd: 96

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40301
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://client1.test.example.com. IN A

;; ANSWER SECTION:
http://client1.test.example.com. 5 IN A 192.168.0.70

;; Query time: 16 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:27 UTC 2022
;; MSG SIZE  rcvd: 75

$ dig -t any @http://192.168.0.253 http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com

; <<>> DiG 9.16.22-Debian <<>> -t any @http://192.168.0.253 http://alias.dummy.example.com http://alias.test.example.com http://client1.test.example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24227
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://alias.dummy.example.com. IN ANY

;; ANSWER SECTION:
http://alias.dummy.example.com. 0 IN CNAME http://client1.test.example.com.
http://client1.test.example.com. 0 IN A 192.168.0.70

;; Query time: 20 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:41 UTC 2022
;; MSG SIZE  rcvd: 114

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12433
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://alias.test.example.com. IN ANY

;; ANSWER SECTION:
http://alias.test.example.com. 5 IN CNAME http://client1.test.example.com.

;; Query time: 20 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:41 UTC 2022
;; MSG SIZE  rcvd: 96

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31132
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;http://client1.test.example.com. IN ANY

;; Query time: 20 msec
;; SERVER: 192.168.0.253#53(192.168.0.253)
;; WHEN: Wed Mar 02 17:34:41 UTC 2022
;; MSG SIZE  rcvd: 59

What if you try 

cname=alias.test.example.com,client1.test.example.com,alias.dummy.example.com,client1.test.example.com

Does it work?