If the company's SSID is not visible in some areas while other networks are still visible, the most likely cause is insufficient wireless coverage. The wireless signal does not reach those areas, meaning additional access points or signal boosters may be required.
Breakdown of Options:
A). Interference or channel overlap - Would cause slow or unstable connections, but the SSID should still be visible.
B). Insufficient wireless coverage - # Correct answer. If the SSID is not appearing, the signal is too weak in that area.
C). Roaming misconfiguration - Would cause devices to stay on weaker APs instead of switching, but the SSID should still be visible.
D). Client disassociation issues - This would disconnect users, but they should still see the network.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 1.6: Explain wireless concepts and technologies.