200-901 Network Fundamentals Practice Question
An engineer is troubleshooting a VoIP call quality issue. The call uses UDP and experiences packet loss. Which characteristic of UDP most likely contributes to the problem?
⚠ Common exam trap
Cisco often tests the misconception that UDP's lack of reliability is always a flaw, but the trap here is that candidates may incorrectly attribute the problem to UDP's lack of ordered delivery or flow control, when the core issue is the absence of retransmission for lost packets.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No retransmission of lost packets
UDP is a connectionless transport protocol that does not provide retransmission of lost packets. In VoIP, packet loss directly degrades call quality because lost audio data is never resent, leading to gaps or distortion in the conversation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Ordered delivery guarantee
Why it's wrong here
UDP provides no ordering guarantee; datagrams may arrive out of sequence, which is not the mechanism causing loss. It is tempting because reordering is a real UDP weakness, and ordered delivery would be the correct answer if the symptom were jitter from out-of-order packets rather than loss.
- ✗
Connection-oriented setup
Why it's wrong here
UDP is connectionless, so no handshake or session state exists; connection-oriented setup describes TCP, not UDP. It is tempting because connection state affects reliability, and TCP's connection-oriented design would be the correct answer if the question asked which protocol guarantees delivery.
- ✓
No retransmission of lost packets
Why this is correct
UDP provides no retransmission mechanism, so datagrams dropped in transit are never recovered, producing gaps that degrade VoIP audio. TCP would retransmit lost segments, but UDP's fire-and-forget design leaves loss concealment entirely to the application codec.
- ✗
Flow control mechanism
Why it's wrong here
UDP has no flow control; it transmits without regard to receiver buffer capacity, so this is not a UDP characteristic causing loss. It is tempting because flow control prevents overflow, and TCP's sliding window would be the correct answer if the question asked how to avoid overwhelming a receiver.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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