CompTIA Network+ Question C-49

Which of the following is MOST likely to use an RJ-11 connector to connect a computer to an ISP using a POTS line?

A. Multilayer switch
B. Access point
C. Analog modem
D. DOCSIS modem

Correct Answer: C

Explanation:
Before ADSL broadband connections became the standard for Internet connections, computers used analog modems to connect to the Internet. By today’s standards, analog modems are very slow typically offering a maximum bandwidth of 56Kbps.
An analog modem (modulator/demodulator) converts (modulates) a digital signal from a computer to an analog signal to be transmitted over a standard (POTS) phone line. The modem then converts (demodulates) the incoming analog signal to digital data to be used by the computer.
An analog modem uses an RJ-11 connector to connect to a phone line (POTS) in the same way a phone does.

CompTIA Network+ Question A-2

An administrator notices an unused cable behind a cabinet that is terminated with a DB-9 connector. Which of the following protocols was MOST likely used on this cable?

A. RS-232
B. 802.3
C. ATM
D. Token ring

Correct Answer: A

Explanation:
A DB-9 connector is used on serial cables. Serial cables use the RS-232 protocol which defines the functions of the 9 pins in a DB-9 connector. The RS-232 standard was around long before computers. It’s rare to see a new computer nowadays with a serial port but they were commonly used for connecting external analog modems, keyboards and mice to computers.