SERVFAIL ... : could not fetch nameservers for 0x20 fallback

Since installing 1.10 and now 1.10.1 I have been seeing these errors:

20/05/2020 12:59:06 C:\Program Files\Unbound\unbound.exe[1760:0] query: 127.0.0.1 www.internic.net. A IN

20/05/2020 12:59:07 C:\Program Files\Unbound\unbound.exe[1760:0] query: 127.0.0.1 www.internic.net. A IN

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] error: SERVFAIL <www.internic.net. A IN>: could not fetch nameservers for 0x20 fallback

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] reply: 127.0.0.1 www.internic.net. A IN SERVFAIL 1.637495 0 34

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] reply: 127.0.0.1 www.internic.net. A IN SERVFAIL 2.640876 0 34

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 www.internic.net. A IN SERVFAIL 2.859629 0 34

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 www.internic.net. A IN

20/05/2020 12:59:09 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 www.internic.net. A IN

The a little bit later all is OK?

20/05/2020 12:59:36 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 www.internic.net. A IN

20/05/2020 12:59:36 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 www.internic.net. A IN NOERROR 0.000000 1 89

This is just one example I also have several others:

20/05/2020 12:58:40 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 www.google.com. A IN

20/05/2020 12:58:41 C:\Program Files\Unbound\unbound.exe[1760:0] query: 127.0.0.1 www.google.com. A IN

20/05/2020 12:58:41 C:\Program Files\Unbound\unbound.exe[1760:0] error: SERVFAIL <www.google.com. A IN>: could not fetch nameservers for 0x20 fallback

20/05/2020 12:58:41 C:\Program Files\Unbound\unbound.exe[1760:0] reply: 127.0.0.1 www.google.com. A IN SERVFAIL 0.781225 0 32

20/05/2020 12:58:41 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 www.google.com. A IN SERVFAIL 1.009289 0 32

20/05/2020 12:58:41 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 www.google.com. A IN

20/05/2020 12:58:42 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 www.google.com. A IN NOERROR 0.078129 0 48

20/05/2020 12:53:29 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 login.live.com. A IN

20/05/2020 12:53:29 C:\Program Files\Unbound\unbound.exe[1760:0] query: 127.0.0.1 login.live.com. A IN

20/05/2020 12:53:30 C:\Program Files\Unbound\unbound.exe[1760:0] error: SERVFAIL <login.live.com. A IN>: could not fetch nameservers for 0x20 fallback

20/05/2020 12:53:30 C:\Program Files\Unbound\unbound.exe[1760:0] reply: 127.0.0.1 login.live.com. A IN SERVFAIL 0.819533 0 32

20/05/2020 12:53:30 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 login.live.com. A IN SERVFAIL 1.038277 0 32

20/05/2020 12:53:30 C:\Program Files\Unbound\unbound.exe[1760:0] query: ::1 login.live.com. A IN

20/05/2020 12:53:30 C:\Program Files\Unbound\unbound.exe[1760:0] reply: ::1 login.live.com. A IN NOERROR 0.078123 0 169

Any thoughts?

I had not changed the configuration only the version of unbound but they seemed to be getting more frequent.

Having had a bit of a dig I found that one of the servers was the cause of the problem:

forward-zone:

name: “.”

forward-tls-upstream: yes

forward-first: yes

Cloudflare DNS

forward-addr: 2606:4700:4700::1111@853#cloudflare-dns.com

forward-addr: 1.1.1.1@853#cloudflare-dns.com

forward-addr: 2606:4700:4700::1001@853#cloudflare-dns.com

forward-addr: 1.0.0.1@853#cloudflare-dns.com

Quad9

#forward-addr: 2620:fe::fe@853#dns.quad9.net

#forward-addr: 9.9.9.9@853#dns.quad9.net

#forward-addr: 2620:fe::9@853#dns.quad9.net

##forward-addr: 149.112.112.112@853#dns.quad9.net

When I comment out the Quad9 Server thing seem to be much better. Are there other servers that can be used so I have an alternative to CloudFlare,

Is there something I could do in the configuration that would tell me which server had been used without ballooning the log file with lots of data?

Is there something I can do in the configuration that would help what ever the issue is that causes the failure which looks like a timeout?