The network engineer is installing Access Points (APs) for a Small Office/Home Office (SOHO) where every staff member uses a cordless phone. The goal is to reduce interference. Let's evaluate the options:
802.11a: Operates in the 5 GHz frequency band. It provides higher data rates but has shorter range and poorer penetration through walls due to its higher frequency. It is less likely to interfere with cordless phones.
802.11b: Operates in the 2.4 GHz frequency band. It has slower data rates but better range and wall penetration. However, it shares the same frequency band with many cordless phones, microwave ovens, and other devices, leading to potential interference.
802.11g: Also operates in the 2.4 GHz frequency band. It provides higher data rates than 802.11b but maintains backward compatibility with 802.11b devices. Like 802.11b, it shares the same frequency band with cordless phones and other devices.
802.1X: This is not a wireless standard. It is an authentication protocol used for network access control.
Given the scenario, 802.11a would work best to reduce interference because it operates in the 5 GHz band, which is less crowded and less likely to overlap with cordless phones.