What causes jitter?

• A. Variable packet delay due to congestion or routing changes.
• B. Constant packet delay.
• C. Packet loss only.
• D. Jitter is caused by wrong codecs.

Answer: (A)

Jitter is the variation in packet arrival times. It occurs when the time it takes for packets to traverse the network isn’t constant, typically due to fluctuating delays from congestion (packets waiting in queues) or routing changes (different paths with different delays). If delays were constant, packets would arrive at steady intervals and jitter would be minimal or zero. Packet loss isn’t what creates jitter, though it can make the overall quality worse; codecs might affect perceived quality but aren’t the root cause of jitter itself. Mitigation comes from stabilizing delays with jitter buffers, QoS, and stable routing.