Score:0

BIND9 is not processing requests

in flag

Having set up a new mail/DNS/DHCP/proxy server based on Ubuntu 20.04.3, I see an odd behavior of the mentioned DNS server. Running nslookup a client is given a persistent DNS request timed out, also this server throws SERVFAIL looking up any valid domain. ISC DHCP server is on. Packet forwarding is enabled in sysctl.conf. Mail services (iRedMail-1.5.1) work properly. Server is pingable for the client and vice versa, also pinging the external domains correctly. The complete set of BIND9 9.18.0 issues are:

  1. Frequent warnings "Unable to fetch DNSKEY set '.': timed out" in the systemctl status bind9's output;
  2. SERVFAIL response to any dig attempt;
  3. Any nslookup attempt is given a "Got SERVFAIL reply from (LAN IP), trying next server" BIND listens to any interface by default, dnssec-validation is set to yes, recursion allowed by the configuration borrowed from a sister server (Zentyal 6.2/BIND 9.11.3-Lubuntu)

Addendum:

  1. Output of netstat -tulpn states that both TCP/53 and UDP/53 are open on all interfaces, also 127.0.0.53:53 being run by systemd-resolved.
  2. Attempt to telnet 192.168.1.3 53 on the testing LAN client results in a failure.
  3. resolv.conf symlink points to a file seemingly generated by bind, containing LAN IP and ISP DNS servers. NB: those forward servers are OK, as the sister server works with them perfectly.
  4. There's UFW turned on, with enabled port 53 in, out and routing.
waltinator avatar
it flag
Are you using a supported Ubuntu release? None of this "based on" nonsense.
in flag
Yes, Ubuntu 20.04.3. BIND9 9.18.0 was configured from sources via `make install` . Can either BIND9 or this Ubuntu version not to support a rather old hardware of this server? I mean Intel SE7320SP2 motherboard and its chipset.
in flag
Upd. UFW is enabled, and doesn't blocking any port 53 traffic or any outgoing traffic at all. Enabled logging in BIND confs and what did I see? A persistent query failed (timed out) for (any site)/IN/A at query.c:7670
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