Domain Zone Forwarder redundancy

IT_Field_Support Posts: 97  Ally Member
First Anniversary Friend Collector First Comment
edited April 2021 in Security
Hi all,

We have noticed some anormal behaviour on our many USG40w and Domaine Zone Forwarder.
We are using 4 DNS server for private zone.
After making some tests, we realise that if the first server on the list was not available for the zone xxx, the DNS request timeout without result.
The router does not failover on the other Domaine Zone Forwarder  as we thought.

Could you tell us if it is a normal behaviour and how should act the Domain Zone Forwarder ? I cannot find any technical documentation on that.



All Replies

  • Zyxel_Emily
    Zyxel_Emily Posts: 1,296  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer

    Hi @IT_Field_Support,

    If USG cannot query the first DNS server, it will then uses the second DNS server to query.

    In this example, create a fake DNS server as the first DNS server and as the second DNS server.

    Connect one laptop in lan1 and open some websites.

    Capture DNS packets in lan1.

    In the packet trace, the first DNS server doesn’t reply. Only the second DNS server replies.

    It means USG uses the second DNS server to query.

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