Network & Infrastructure / Segmentation, TLS & Secure Connectivity
Egress DNS policy and direct-resolution bypass paths
Clients are required to use enterprise resolvers, yet some applications resolve names through external encrypted services. Blocking only UDP port 53 does not express the complete policy.
Environment and inputs: Stateful network boundaries, TLS endpoints and IPsec gateways; use the deployed security policy and implementation manual. Diagnostic/design example; not tested on production equipment.
Collect the evidence
Inventory configured resolvers, application transport behavior, approved encrypted DNS endpoints and observed egress destinations. Distinguish a policy exception from an unintentional bypass.
Explain the result
DNS resolution can use several transports and application-controlled paths. Port-based restrictions alone may not enforce organizational resolver ownership or provide the desired name-resolution telemetry.
Plan the fix
Define the supported resolver and encrypted-transport policy explicitly, using endpoint and network controls appropriate to the environment. Preserve necessary privacy and application requirements in the design.
Check the result and rollback
Test approved resolution, documented exceptions and blocked bypass scenarios. Revert if enforcement breaks required services or collects broader traffic than the intended operational purpose.