If internal resources like shared drives, intranet sites, or domain controllers suddenly become unreachable after deploying DNSFilter, incorrect local domain and resolver settings are often the culprit. Without proper configuration, DNS queries meant for internal servers may be sent to external resolvers, leading to failed lookups and service disruptions.

How to Fix Local Domain Resolution Issues

To restore access to internal resources, follow these steps based on your network setup:

For Roaming Clients

Roaming Clients automatically detect the original DNS configuration before enforcing policies. However, for internal domains to bypass filtering:

1. Add required local domains to the Local Domains list in the DNSFilter dashboard
2. Ensure local resolvers are specified—without them, local domains will still be filtered
3. Verify that the device is receiving the correct local DNS server via DHCP

For DNS Relay Deployments

Unlike Roaming Clients, the DNS Relay does not automatically detect internal resolvers and must be configured manually:

1. Add the local resolver IP(s) in the Relay configuration file to direct internal traffic correctly
2. Ensure .local domains are correctly forwarded—these are automatically routed, but all other internal domains must be explicitly specified
3. Test internal lookups using nslookup or dig to confirm queries are being resolved by the correct DNS server

For Networks Using Split Tunneling or Multiple Segments

In complex environments where VPNs, VLANs, or multiple subnets exist, additional considerations apply:

• Confirm that DNS settings allow queries to route to the appropriate local resolver
• If using a VPN, ensure DNS traffic for internal resources is tunneled correctly
• Consider setting up conditional forwarding if some domains require different resolvers

Final Checks and Troubleshooting

If local DNS resolution issues persist, check the following:

✅ Firewall rules allow internal DNS queries to pass through
✅ Devices are correctly receiving local DNS settings via DHCP
✅ No conflicting settings override local resolution preferences

Properly configuring local domains and resolvers prevents internal resource downtime while maintaining security. If setup issues persist, refer to your DNSFilter dashboard or comment below for further assistance.