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martyyy
martyyy
Explorer III
October 31, 2024
Question

DNS Server in the Interface set as Interface IP

  • October 31, 2024
  • 1 reply
  • 2966 views

Hi,

In one of our Interface (Explorer Data), the DNS Server was set as "Same as Interface IP".
1. What DNS will the end device will be getting? We would like to know what DNS it was using if the end device uses FQDN, how it resolves its FQDN to IP Address.

 

DNS Servers - Specify
Primary DNS server - 1.1.1.1
Secondary DNS - 8.8.8.8

 

2. For the "dynamically obtained DNS server", what is its purpose? Is it the "same as interface IP", and would this be used to rely on the DNS server or FortiGuard?"

 

Appreciate your comments and Thank you in advance.Same as Interface IP.jpg

1 reply

pminarik
Staff
pminarik
Staff
October 31, 2024

The client will get the IP of that interface.

E.g. if you are editing interface "port1" with IP 192.168.123.45 and select DNS='same as interface IP', DHCP will give 192.168.123.45 as the DNS server IP.
Warning: There is no verificaction if the DNS server is enabled on this interface/IP. That is up you you to do separately.

 

Thus the three options are:

"same as interface IP": Client's DNS IP will be the IP of this FGT interface.

"same as system DNS": Client's DNS IPs will be the IPs configured in Network > DNS (in FGT GUI)

"specify": manually set here to anything you want.

 

-----------------------------

 

"Dynamically obtained DNS servers": This is a list of DNS servers learned from upstream DHCP/PPPoE. It only shows when one of your FGT interfaces is a DHCP/PPPoE client and it received a DNS IP from there. You may or may not use it, depending on the interface's setting. ("override internal DNS = enable" => use the DHCP/PPPoE-learned DNS IP)

    martyyy
    martyyyAuthor
    Explorer III
    November 4, 2024

    Hi @pminarik ,

    Appreciate your response.

     

    Just to add, Client's DNS IP will be the IP of this FGT interface.

    how or what is the process to resolve FQDNs if the DNS is the FGT interface?

    Thank you!

    pminarik
    Staff
    pminarik
    Staff
    November 4, 2024

    You need to enable and configure DNS resolver on that interface/IP.
    1, System > Feature Visibility > make sure "DNS Database" is enabled (to see the options in the GUI)

    2, Network > DNS Servers > DNS Service on Interface

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