What is a risk of lowering port scan timeouts too much?

• A. Missing important packets
• B. Slowing down the scan
• C. Increasing false positives
• D. Overloading DNS

Answer: (A)

Lowering port scan timeouts means you aren’t waiting long enough for a reply after sending a probe. If a host is slow to respond—due to network latency, congestion, rate limiting, or firewall processing—you’ll miss its response. The port may actually be open, but because the scanner gave up too quickly, that openness isn’t recorded. That’s a false negative: you fail to discover an available service because the timeout was too aggressive.

The other outcomes don’t fit as well: shorter timeouts don’t slow down the scan; they speed it up but at the cost of reliability. Timeouts aren’t the primary driver of false positives (misinterpreting noise as a response) or DNS load; those are caused by other factors like how responses are interpreted or whether hostnames are resolved during scanning.