Unbound does not response a forwarded query

Unbound
1

Hi there,

I am using unbound to forward mine.intra which is a private domain of Microsoft Windows Active Directory due to DNS server on Windows server has the record.

first of all, there is a record file.mine.intra created on DNS server on Windows, and works for clients via running “dig file.mine.intra @IP-OF-WINDOWS”.
Second, create forward configuration in unbound.conf and restart Unbound, details are listed below. But Unbound is not able to response to client which run “dig file.mine.intra@IP-OF-UNBOUND”

forward-zone:
name: “mine.intra.”
forward-addr: 10.3.3.21
forward-addr: 10.3.3.22
forward-first: no

(10.3.3.21 is dc1 of mine.intra, 10.3.3.22 is dc2 of mine.intra.)
Finally, I use tcpdump -w to catch packages and save to a file to see that happens. Then using Wireshark to open capture file I get below result.
Time source. Dest. Protocol. Length. Info.
7.841795 client_ip. Unbound_ip. DNS 76 Standard query 0xb80a A file.mine.intra
7.842781 Unbound_ip Windows_ip. DNS 87 Standard query 0xdece A file.mine.intra OPT
7.843769. ReltekU_e9:.. Broadcast ARP 60 Who has IP_OF_Unbound? Tell IP_OF_Windows
7.843788. ReltekU_64.. ReltekU_e9:.. ARP 42 IP_OF_Unbound is at 52:54:00:64:37:c7
7.844291. Windows_ip. Unbound_ip. DNS 103 Standard query response 0xdece A file.mine.intra A 10.3.3.50 OPT
7.844761. Unbound_ip. 192.8.128.30. DNS 70 Standard query 0x8762 NS OPT

Clearly Windows response the query but Unbound do not receive it and forward response to client, however it continually query ROOT DNS. BTW, these is also standard private domain forwarding settings (same format like above) in the same unbound.conf and works well, such as my-private-domain.com forwarded to a BIND server.

Why this happens and how to make Unbound response client if query a host in xxx.intra?

Thanks in advance.

Adrian

2

When I check Unbound cache, it shows

unbound-control dump_cache|grep mine.intra
file.mine.intra. 86387 IN A 10.3.3.50
msg file.mine.intra. IN A 33152 1 47 1 1 0 0
file.mine.intra. IN A 0

3

Hi Adrian,

Unbound waits until the root has done. But you do not allow these
queries to be done.

You can stop unbound from querying the root NS by setting a forward zone
for the root (".") to somewhere.

Best regards, Wouter

4

Hey Wouter,

Thanks a lot for solution. I create “.” forwarding settings in unbound.conf and restart the Unbound service, unfortunately client still can not receive the response from Unbound.

5

Hi Adrian,

Looks like it could be SERVFAIL because of DNSSEC. Is intra not signed,
but you don't have domain-insecure: "intra" ? Or is there some other
DNSSEC failure? dig +cdflag, or get validation error from unbound logs.

Best regards, Wouter

6

Hey Wouter,

Thanks for further suggestion which is really help. intra is for sure not signed and there is no domain-incure settings.
Run dig +cdflag on client can get correct answer.

Once I create domain-insecure setting in unbound.conf, it works!

Replay the full picture:

Windows Server version: Windows Server 2012 R2 Standard Edition, pure clean initial installation with AD and DNS. Double DCs.
Unbound is used as DNS routing, forwarding domain which created on Windows AD and DNS.

The first stage, I create Windows AD with DNS and domain was set as standard model like intra.my-domain.com., at this stage, Unbound forwarding works from client point of view.
Second stage, I reinstall Windows AD with DNS and domain was set as private model like mine.intra. , at this stage, from client point of view, Unbound forwarding failed until setting domain-insecure: “mine.intra” in unbound.conf.

This case tells me, Windows AD set private domain into not-signed or insecure model but set standard domain into secure model by default. Which is root cause.