Omnidirectional (or omni) antennas are the most commonly used wireless antenna on access points and wireless devices, but there are others. If you're planning on taking the Security+ exam, you should have a basic understanding of the different types of wireless antennas, and their purpose.
For example, can you answer this sample Security+ question?
Q. You need to provide connectivity between two buildings without running any cables. You decide to use two WAPs and a high-gain directional antenna. Which of the following antennas is the BEST choice to meet this need?
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available here.