VM Scans Ending with No Host Alive

Problem

The No Host Alive scan status appears. Hosts are shown under the "Hosts Not Alive" section of scan results.

Cause

The No Host Alive scan status appears when the scanner does not detect the target to be alive during the Discovery phase of the scan. Hosts are shown under the "Hosts Not Alive" section of scan results.

Solution

• Verify if the IP is not listed in Exclude Hosts under Scans Setup (Scans>Setup>Excluded Hosts). If the IP is excluded, it will also be excluded from maps and scans.

• Check the tracking method. If the tracking method is either NetBIOS or DNS and name resolution fails, then the host is returned as not alive.

• Check Option Profile for the 13 ports TCP and 6 ports UDP which the scanner discovers at the time of host discovery. It is necessary for at least one of these ports to be open. Additionally, you can include any other open ports on the host to help discover it.

• Ensure that the scanner and target IP are able to communicate with each other. If you're performing an external scan, you will need to whitelist Qualys' IP range (found under VM > Help > About). To confirm that the Qualys system receives positive replies, use commands such as Ping, Traceroute, and nslookup.

• Refer to the following articles:

  • How Vulnerability Management scans work in the background

  • Troubleshooting "Hosts Not Alive"

  • Host Alive Testing