A customer has several remote sites connected with their headquarters through microwave links. An engineer must propose a backup WAN solution based on these conditions: Which backup WAN link type…

LTE (Long-Term Evolution, encompassing 4G and 5G cellular technologies) provides a highly available, geographically diverse, and typically reliable wireless connection. This makes it an excellent choice for a backup WAN, as it operates independently of the fixed microwave link's line-of-sight requirements and infrastructure.

802.16 WiMAX is an older wireless technology that saw limited adoption and is largely superseded by LTE, making it a less common and less supported backup option today.

A Laser link (Free Space Optics) requires line-of-sight and can be susceptible to similar environmental factors like fog or heavy rain as microwave, reducing its diversity as a backup.

802.15.1 Bluetooth is a very short-range wireless technology designed for personal area networks and is completely unsuitable for WAN connectivity.