In Huawei's smart roaming solution, which of the following methods can be used by a...

In Huawei’s smart roaming solution, the WAC can discover and maintain neighboring AP entries of STAs by using two methods: passive listening and active scanning. Passive listening means that the AP listens to the Probe frames sent by STAs and reports them to the WAC. Active scanning means that the AP periodically and proactively scans neighboring APs of STAs and reports them to the WAC.

References: https://support.huawei.com/enterprise/en/doc/EDOC1100058940/8a8f1c9b/smart-roaming