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200-901 Practice Question: Which TWO of the following are functions of the…
Which TWO of the following are functions of the transport layer in the OSI model? (Choose two.)
⚠ Common exam trap
Cisco often tests the distinction between transport layer functions (segmentation, reliability) and data link layer functions (error detection via trailer), so candidates mistakenly assign trailer-based error detection to the transport layer instead of the data link layer.
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
✓
Segmentation and reassembly of data.
Segmentation and reassembly of data is a core function of the transport layer. The transport layer (e.g., TCP) takes data from the session layer, breaks it into smaller segments (segmentation), assigns sequence numbers, and then reassembles these segments in the correct order at the destination. This allows large data streams to be transmitted efficiently over the network layer, which has a maximum transmission unit (MTU) size.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Segmentation and reassembly of data.
Why this is correct
Transport layer segments data and reassembles it at the destination.
- ✓
Providing reliable data transfer with acknowledgements.
Why this is correct
TCP provides reliability; this is a transport layer service.
- ✗
Adding a trailer for error detection.
Why it's wrong here
This occurs at the data link layer.
- ✗
Encrypting data for secure transmission.
Why it's wrong here
Encryption is a presentation layer function.
- ✗
Determining the best path to a destination.
Why it's wrong here
This is a network layer function.
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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.