hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A network administrator notices that a critical…
A network administrator notices that a critical database server is responding slowly. The server uses both TCP and UDP for different services. Which of the following is a characteristic of UDP that could explain performance issues under heavy load?
⚠ Common exam trap
A common misconception is that UDP is always faster or more reliable under load, when in fact its lack of flow control and retransmission can cause performance degradation in high-traffic environments.
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
✓
UDP does not guarantee packet delivery or order
UDP is a connectionless transport protocol that does not guarantee packet delivery, ordering, or error recovery. Under heavy load, if the database server receives UDP datagrams out of order or loses packets, the application layer must handle retransmissions and reassembly, which can degrade performance. This lack of reliability and flow control means UDP can overwhelm a server with traffic it cannot manage, leading to slow responses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
UDP retransmits lost packets automatically
Why it's wrong here
UDP, or User Datagram Protocol, is a connectionless protocol that does not incorporate mechanisms for automatic packet retransmission. Unlike TCP, UDP simply sends data packets without confirming their receipt or maintaining state about sent packets. If a UDP packet is lost in transit, the protocol itself does not detect the loss or initiate a retransmission, leaving such error recovery responsibilities to the application layer if required.
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UDP uses a three-way handshake to establish a connection
Why it's wrong here
UDP operates as a connectionless protocol, meaning it does not establish a dedicated connection or session between the sender and receiver before transmitting data. Consequently, UDP does not utilize a three-way handshake, which is a fundamental feature of connection-oriented protocols like TCP, used to synchronize sequence numbers and acknowledge readiness for data transfer. Instead, UDP sends datagrams immediately without any prior negotiation or setup overhead.
- ✓
UDP does not guarantee packet delivery or order
Why this is correct
The User Datagram Protocol (UDP) is inherently an unreliable transport protocol, meaning it offers no guarantees regarding the successful delivery of packets to their destination. Packets sent via UDP may arrive out of sequence, be duplicated, or be lost entirely without any notification to the sender. This lack of reliability and ordering ensures minimal overhead, making it suitable for applications where speed is prioritized over absolute data integrity or where minor data loss is acceptable.
- ✗
UDP provides flow control to prevent congestion
Why it's wrong here
UDP does not implement any form of flow control mechanisms designed to prevent a sender from overwhelming a receiver or the network. It transmits data as quickly as the application layer provides it, irrespective of the receiver's processing capacity or network congestion. This absence of flow control can lead to buffer overflows at the receiver or increased network congestion and packet loss, as there is no feedback loop to regulate the sending rate.
Visual reference
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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