Options Port Scan screen

This screen allows you to configure the port scan options:

Highest port number to scan

ZAP will start from 1 and work up to this port number.
Selecting a high number will significantly increase the time a port scan takes.

Concurrent scanning threads per host

The number of threads the scanner will use per host.
Increasing the number of threads will speed up the scan but may put extra strain on the computer ZAP is running on and the target host.