How to fix a "THROWAWAY" response

[RayG]

Hi,

To answer my own question,

I went back to unbound V1.17.1 and I do not have the problem I described
below.

So I am at a loss to say why this is happening.

The only difference to make the web site work with V1.18.0 is to turn off
ipv6

So until I can get some pointers as to what is happening I will stay with
V1.17.1

RayG

-----Original Message-----
From: RayG <rgsub1 at btinternet.com> 
Sent: Sunday, September 3, 2023 4:54 PM
To: unbound-users at lists.nlnetlabs.nl
Subject: How to fix a "THROWAWAY" response

Hi,

I have been trying to get a web site to work correctly with V1.18.0. I have
not reverted yet to a previous version of unbound but I have been trying to
access a part of this web site I have not tried before.

What I have found is that if Unbound has

do-ip6:  yes 

then the site does not work. If I set 

do-ip6: no

Then it appears to work OK.

This maybe the first of many discovery steps. My system is able to do both
IPV6 and IPV4 so I don't think that setting:

do-nat64: no

to yes will make and difference and I am not 100% certain regarding nat64
anyway. This is all a bit trial and error on my part as I am certainly not a
DNS expert. I do not want to post publicly any of the verbose: 4 log file as
it is a banking web site.

Any suggestions would be welcome.

Thanks 

When I start the access to the web site there are two records returning the
IPV4 (A) address and then we get multiple tries for the same name looking
for an IPV6 (AAAA or HTTPS) and it all ends up with SERVFAIL so I don't
thing the IPV4 address is ever returned hence the web site does not work.
Just my 2ps worth.

What I see is unbound trying all the upstream servers:

;; flags: qr rd ra ; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;;
QUESTION SECTION:
<dns name>.	IN	AAAA

;; ANSWER SECTION:

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:
;; MSG SIZE  rcvd: 41
03/09/2023 15:48:06 C:\Program Files\Unbound\unbound.exe[5672:0] debug:
iter_handle processing q with state QUERY RESPONSE STATE
03/09/2023 15:48:06 C:\Program Files\Unbound\unbound.exe[5672:0] info: query
response was THROWAWAY

Or:

;; flags: qr rd ra ; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;;
QUESTION SECTION:
<dns name>.	IN	HTTPS

;; ANSWER SECTION:

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:
;; MSG SIZE  rcvd: 41

03/09/2023 15:48:06 C:\Program Files\Unbound\unbound.exe[5672:0] debug:
iter_handle processing q with state QUERY RESPONSE STATE
03/09/2023 15:48:06 C:\Program Files\Unbound\unbound.exe[5672:0] info: query
response was THROWAWAY