220-1101 Question 137
Single answerDigital subscriber line (DSL)A technician is setting up internet service for a small office that uses DSL over the existing telephone wiring. The office manager reports that internet access works, but every time someone makes or receives a phone call, the DSL connection drops and has to reconnect. Which of the following is the MOST likely cause of the problem?
- A
A DSL filter is missing on one of the telephone devices sharing the line
- B
The wireless router is using the wrong SSID broadcast setting
- C
The modem should be connected with RG-6 coax instead of the current phone cable
- D
The ISP assigned a private IP address instead of a public IP address
Show answer and explanation
Correct answer: A
Explanation
The best answer is the missing DSL filter on a telephone device. DSL operates over standard copper telephone lines while using higher frequencies than analog voice service. To prevent voice devices from interfering with the DSL signal, filters are installed on phones, fax machines, and similar devices sharing the line; the DSL modem itself is typically not filtered. A common troubleshooting best practice for intermittent DSL drops during calls is to verify that every non-DSL device on the line has a microfilter and that the modem is connected correctly, ideally to a dedicated jack if available. This aligns with standard vendor and ISP installation guidance for ADSL/DSL deployments.
- A. Correct.
This is correct. DSL shares the same copper telephone line as voice service, but the frequencies used for voice and DSL are separated. If a phone, fax machine, or other voice device on the line does not have a proper DSL microfilter installed, voice activity can introduce interference that disrupts the DSL signal and causes the modem to lose sync. This is a common real-world DSL issue and one of the first things a technician should check.
- B. Incorrect.
This is incorrect. SSID broadcast settings affect whether wireless clients can easily see the Wi-Fi network name, but they do not cause a DSL connection to drop specifically when a phone call is made. Someone might choose this if they are thinking generally about connectivity issues, but the symptom points to the phone line rather than Wi-Fi configuration.
- C. Incorrect.
This is incorrect. Traditional DSL service uses twisted-pair telephone cabling and an RJ-11 connection, not RG-6 coaxial cable. Coax is commonly associated with cable internet, not DSL. This distractor targets the misconception that all broadband services use coax.
- D. Incorrect.
This is incorrect. IP addressing from the ISP would not normally cause the connection to fail only during phone calls. Whether the ISP uses public addressing directly on the modem/router or private addressing behind carrier infrastructure is unrelated to line interference caused by voice calls. This option is plausible to candidates thinking about WAN setup, but it does not match the symptom pattern.