This command will scan the host 192.168.1.20 on port 80 using the following options:
* -A: This option enables OS detection, version detection, script scanning, and traceroute. This will help to determine if the host is running an approved version of Linux and a patched version of Apache, as well as other information about the host and the network path.
* -T4: This option sets the timing template to aggressive, which speeds up the scan by increasing the number of parallel probes, reducing the timeouts, and assuming faster responses.
* -p80: This option specifies the port to scan, which is 80 in this case. Port 80 is commonly used for HTTP services, such as Apache web server.