FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
ManpreetSingh
Article Id 427125
Description This article describes the issue of DNS resolution not working over a remote access IPsec tunnel. It provides a step-by-step guide to resolving the issue by configuring the DNS suffix in the IPsec Phase 1 interface.
Scope FortiGate.
Solution

To resolve the issue of DNS resolution not working over a remote access IPsec tunnel, follow these steps:

  1. Go to VPN -> IPsec -> Phase 1 and edit the existing phase 1 configuration.
  2. In the phase 1 configuration, enable Unity Support and set the Domain to the desired DNS suffix.
  3. The configuration should look like this:


config vpn ipsec phase1-interface
    edit <name>
        set unity-support enable
        set domain <string>
    next
end

 

  1. After making the changes, disconnect and reconnect the VPN client to test the DNS resolution.

 

By following these steps, the DNS suffix will be configured correctly, and DNS resolution should work as expected for short hostnames over the remote access IPsec tunnel.