CompTIA Network+ (N10-009)Network TroubleshootingHard
A network administrator is troubleshooting an issue where a newly deployed VoIP phone system is experiencing frequent call drops and garbled audio. A packet capture reveals significant packet reordering and high jitter values. The network infrastructure consists of several switches and routers. Which of the following is the MOST likely cause of these symptoms?
- AInsufficient bandwidth on the network links.
- BMissing Quality of Service (QoS) configuration.
- CIncorrect VLAN assignments for VoIP traffic.
- DDuplex mismatch on a network switch port.
Show answer & explanationAnswer & explanation
Correct answer: B. Missing Quality of Service (QoS) configuration.
Frequent call drops, garbled audio, packet reordering, and high jitter are classic symptoms of real-time traffic (like VoIP) being negatively impacted by network congestion or inconsistent packet delivery. Missing QoS configuration means that VoIP traffic is not being prioritized over other, less time-sensitive traffic, leading to these issues in a busy network.
Why the other options are wrong
- A. Insufficient bandwidth could contribute, but high jitter and packet reordering specifically point to a lack of prioritization rather than just raw capacity. QoS directly addresses these real-time concerns.
- C. Incorrect VLAN assignments would likely prevent any connectivity for the VoIP phones, not just cause call drops and garbled audio after initial connection.
- D. Duplex mismatch causes severe, persistent performance issues and collisions, which would manifest as more general network slowness and errors rather than specifically high jitter and packet reordering for VoIP.
Quality of Service (QoS)
Network mechanisms that ensure certain traffic types (e.g., VoIP, video) receive preferential treatment over others to guarantee performance requirements.
- Prioritizes critical traffic to reduce latency, jitter, and packet loss.
- Achieved through classification, marking, queuing, and policing.
- Essential for real-time applications like VoIP and video conferencing.
Memory trick: Voice calls breaking up? They need VIP treatment!