2.2.5 Unbound SERVFAIL after connectivity interruption


  • LAYER 8 Netgate

    I've been seeing something strange. My switch at home started rebooting (a separate issue that will be soon corrected) and after it comes back up, unbound refuses to resolve names.  I can stop it, restart it, and it still returns "SERVFAIL" to all queries.

    I have my cable and DSL modems (Multi-WAN) going through blank VLANs on the switch, so both lose link when the switch reboots.

    Both seem to come back up fine and I can ping out by IP address.

    Looks like I closed the window with my dig history, but it instantly returns SERVFAIL even after a restart of unbound.

    Rebooting pfSense clears it.

    This is consistent and repeatable - All I have to do is bounce the switch.

    The only thing I'm doing special is sourcing all unbound queries from LAN address to facilitate queries across OpenVPN tunnels.


  • LAYER 8 Netgate

    Had some time to bounce this a couple more times this morning and take a closer look.  This was not related to unbound at all.  There were a couple issues at play.

    The first was somehow I ended up without an IPv4 default gateway set. I have Multi-WAN configured so traffic from the LANs was being policy routed out the Tier 1 but traffic from the firewall itself such as unbound queries had no route after a switch reboot.

    The second issue was a couple VLAN assignments not saved in the switch config. This is where things can get a little dicey when you're mixing inside and outside traffic on the same physical switch. I generally consider it safe - until a mistake is made.

    An SG300-52 is on the way to replace this failing D-Link.


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