200-901 Network Fundamentals Practice Question
Which transport layer protocol is used by HTTP and guarantees reliable delivery?
⚠ Common exam trap
Cisco often tests the distinction between transport layer protocols by pairing HTTP with TCP, but the trap here is that candidates may confuse HTTP's use of TCP with other protocols like UDP (used by DNS or VoIP) or think IP provides reliability, when in fact IP only handles routing and fragmentation without delivery guarantees.
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
✓
TCP
HTTP relies on TCP (Transmission Control Protocol) as its transport layer protocol because TCP provides reliable, connection-oriented data delivery. TCP ensures that all HTTP requests and responses are delivered in order, without loss or duplication, by using acknowledgments, retransmissions, and sequence numbers. This reliability is essential for HTTP, which expects complete and correct data transfer for web pages and resources.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
TCP
Why this is correct
TCP provides connection-oriented, reliable delivery through sequence numbers, acknowledgements and retransmission of lost segments, which HTTP requires. UDP, by contrast, is connectionless and offers no delivery guarantee. This satisfies the stem's requirement for a transport layer protocol guaranteeing reliable delivery for HTTP traffic.
- ✗
ICMP
Why it's wrong here
ICMP carries network-layer diagnostics such as echo requests and unreachable messages; it provides no ports, no sessions and no delivery guarantees, so it cannot transport HTTP. It is tempting because ping and traceroute rely on it to test reachability, which is the correct choice when diagnosing connectivity rather than serving web traffic.
- ✗
IP
Why it's wrong here
IP operates at the network layer, providing addressing and routing rather than the transport-layer reliability HTTP requires. It is the right answer when asked which protocol delivers packets between hosts across interconnected networks, not which guarantees ordered, acknowledged delivery.
- ✗
UDP
Why it's wrong here
UDP is a transport-layer protocol but provides connectionless, best-effort delivery with no acknowledgements or retransmission, so it cannot guarantee reliability. It is the right choice for latency-sensitive traffic such as DNS queries, DHCP and streaming media.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.