- A
DHCP
DHCP uses UDP for client-server communication.
- B
SSH
Why wrong: SSH uses TCP for reliable, encrypted remote login.
- C
SMTP
Why wrong: SMTP uses TCP for email delivery.
- D
DNS
DNS uses UDP for queries and responses (though TCP is used for large responses).
- E
NTP
NTP uses UDP for time synchronization.
Question 866 of 1,000
200-901 Network Fundamentals Practice Question
This 200-901 practice question tests your understanding of network fundamentals. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer is analyzing traffic and needs to identify which applications use UDP. Which three applications commonly use UDP as their transport protocol? (Choose three.)
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
✓
DHCP
DHCP (Dynamic Host Configuration Protocol) uses UDP as its transport protocol because it relies on connectionless, best-effort delivery for broadcasting IP configuration requests and offers. DHCP clients send discovery messages to UDP port 67 (server) and servers respond to UDP port 68 (client), avoiding the overhead of TCP's connection establishment, which is unnecessary for transient broadcast-based transactions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DHCP
- ✗
SSH
- ✗
SMTP
- ✓
DNS
- ✓
NTP
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between control plane protocols (like DHCP, DNS, NTP) that use UDP for efficiency versus management or data transfer protocols (like SSH, SMTP) that require TCP's reliability, leading candidates to mistakenly associate all 'important' traffic with TCP.
Detailed technical explanation
How to think about this question
UDP provides a lightweight, stateless transport with no handshake or retransmission, making it ideal for applications like DHCP, DNS, and NTP where speed and low latency are critical, and occasional packet loss is acceptable. For example, DNS queries (UDP port 53) use a single request-response exchange, falling back to TCP only when the response exceeds 512 bytes (per RFC 1035). NTP (UDP port 123) relies on precise timestamps and tolerates lost packets by simply waiting for the next synchronization interval.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this 200-901 question test?
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DHCP — DHCP (Dynamic Host Configuration Protocol) uses UDP as its transport protocol because it relies on connectionless, best-effort delivery for broadcasting IP configuration requests and offers. DHCP clients send discovery messages to UDP port 67 (server) and servers respond to UDP port 68 (client), avoiding the overhead of TCP's connection establishment, which is unnecessary for transient broadcast-based transactions.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
This 200-901 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-901 exam.
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