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Question 928 of 1,052
mediummulti selectObjective-mapped
CCNA Practice Question: Which TWO statements correctly describe the…
This 200-301 practice question tests your understanding of 200-301 exam topics. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO statements correctly describe the encapsulation process at the OSI model Transport 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
✓
It breaks data into smaller units called segments (for TCP) or datagrams (for UDP).
The Transport layer (Layer 4) segments data from the upper layers, adds a header containing source and destination port numbers, and creates segments (TCP) or datagrams (UDP). This process is called encapsulation. The PDU at this layer is a segment (TCP) or datagram (UDP).
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It adds source and destination IP addresses to the data.
Why it's wrong here
Adding IP addresses is a function of the Network layer (Layer 3), not the Transport layer.
- ✓
It breaks data into smaller units called segments (for TCP) or datagrams (for UDP).
- ✗
It adds a header that includes source and destination MAC addresses.
Why it's wrong here
MAC addresses are added at the Data Link layer (Layer 2), not the Transport layer.
- ✓
It adds a header that includes source and destination port numbers.
Why this is correct
The Transport layer header contains port numbers to identify the sending and receiving applications.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
It converts data into bits for transmission over the physical medium.
Why it's wrong here
Conversion to bits occurs at the Physical layer (Layer 1), not the Transport layer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓It breaks data into smaller units called segments (for TCP) or datagrams (for UDP).Correct answer▾
Why this is correct
The Transport layer segments upper-layer data into manageable units. For TCP, these are called segments; for UDP, they are called datagrams.
✗It adds source and destination IP addresses to the data.Wrong answer — click to see why▾
Why this is wrong here
The Transport layer uses port numbers, not IP addresses. IP addresses are added during Network layer encapsulation.
✗It adds a header that includes source and destination MAC addresses.Wrong answer — click to see why▾
Why this is wrong here
MAC addresses are used for local delivery on a network segment and are part of Layer 2 encapsulation.
✗It converts data into bits for transmission over the physical medium.Wrong answer — click to see why▾
Why this is wrong here
The Physical layer handles the actual transmission of raw bits over the network medium.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 200-301 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: It breaks data into smaller units called segments (for TCP) or datagrams (for UDP). — The Transport layer (Layer 4) segments data from the upper layers, adds a header containing source and destination port numbers, and creates segments (TCP) or datagrams (UDP). This process is called encapsulation. The PDU at this layer is a segment (TCP) or datagram (UDP).
What should I do if I get this 200-301 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
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