A spectrum analyzer is the proper tool for identifying and analyzing interference in a wireless network. It allows the technician to see the strength and frequency of all RF signals in the area, helping identify sources of interference that may be affecting the wireless channels and causing performance issues. Incorrect answers include tools and protocols that are useful in other contexts: A protocol analyzer would help capture and analyze packets, not interference frequencies, and a multimeter would measure electrical properties such as voltage and resistance, not RF signals. A cable tester is for checking the integrity of wired cabling, not wireless interference.