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Reliable open port testing for modern engineers

DNS

Master DNS 53 operations

Pair redundancy with rate limiting to keep queries fast and abuse-resistant.

Default port
53
Protocol
UDP / TCP
Primary use
Domain name resolution

Why DNS 53 matters

Every service depends on DNS; a misstep on port 53 cascades into outages.

  • Immediate actions

    Deploy secondary resolvers, health checks, and anycast to absorb failures.

  • Operational guardrails

    Enable response rate limiting and detailed logging to deter amplification attacks.

DNS 53 port guide