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From: Andy Burns <usenet@andyburns.uk>
Newsgroups: comp.misc
Subject: Re: Public DNS Services
Date: Wed, 4 Sep 2024 10:19:30 +0100
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Lawrence D'Oliveiro wrote:

> Andy Burns wrote:
> 
>> use nslookup instead
> 
> Doesn’t seem to have the equivalent of the “-a” option of host.
> 
>      host -a dns.google. | grep -c '^dns'
>      26
> 
> I get 26 lines of info; how many lines do you get?

windows
=======
C:\Users\Andy>nslookup dns.google. 192.168.1.1
Server:  UnKnown
Address:  192.168.1.1

Non-authoritative answer:
Name:    dns.google
Addresses:  2001:4860:4860::8844
           2001:4860:4860::8888
           8.8.4.4
           8.8.8.8

wsl2
====

root@YogaHome:~# nslookup dns.google. 192.168.1.1
Server:         192.168.1.1
Address:        192.168.1.1#53

Non-authoritative answer:
Name:   dns.google
Address: 8.8.4.4
Name:   dns.google
Address: 8.8.8.8
Name:   dns.google
Address: 2001:4860:4860::8844
Name:   dns.google
Address: 2001:4860:4860::8888



the "host -a" seems to rely on the DNS server supporting queries over 
TCP as well as UDP, my Draytek router only supports UDP

root@YogaHome:~# host -a dns.google. 192.168.1.1
Trying "dns.google"
Trying "dns.google"
;; Connection to 192.168.1.1#53(192.168.1.1) for dns.google. failed: 
timed out.
;; no servers could be reached


Using other DNS servers which do support TCP, the amount of info 
returned seems to depend on what types of RR they support, mainly DNSSEC?

root@YogaHome:~# host -a dns.google. 9.9.9.9 | wc -l
27
root@YogaHome:~# host -a dns.google. 8.8.8.8 | wc -l
42
root@YogaHome:~# host -a dns.google. 94.247.43.254 | wc -l
17