The answer is multimode fiber, specifically OM3 or OM4. This is correct because the 10GBASE-SR SFP+ module is designed for short-range transmission over multimode fiber, using a 850 nm wavelength that travels efficiently through the larger core of multimode cable, supporting distances up to 300 meters. On the CompTIA A+ Core 1 220-1201 exam, this question tests your understanding of fiber optic transceiver compatibility, often appearing in scenarios where a technician must match the SFP module to the correct cable type. A common trap is assuming single-mode fiber works with any SFP, but 10GBASE-SR is optimized exclusively for multimode; using single-mode would result in signal loss or no link. To remember this, think of “SR” as “Short Range” for multimode, while “LR” (Long Range) pairs with single-mode.
220-1201 Common Networking Hardware Practice Question
This 220-1201 practice question tests your understanding of common networking hardware. 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.
A technician is installing a new network switch in a server room. The switch has 48 ports and needs to connect to the existing network backbone via fiber optic cable. The technician has a 10GBASE-SR SFP+ module. Which type of fiber optic cable should be used to ensure compatibility?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Multimode fiber (OM3)
10GBASE-SR is designed for multimode fiber (MMF) over short distances, typically up to 300 meters. Using single-mode fiber (SMF) would not work because the transceiver is optimized for multimode. The correct answer is multimode fiber (OM3 or OM4).
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.
✗
Single-mode fiber (OS2)
Why it's wrong here
Single-mode fiber is for long distances and requires a different transceiver (e.g., 10GBASE-LR); 10GBASE-SR is not compatible.
✓
Multimode fiber (OM3)
Why this is correct
10GBASE-SR is designed for multimode fiber, and OM3 supports 10 Gbps up to 300 meters.
Related concept
Static NAT maps one inside address to one outside address.
✗
Cat6a twisted pair
Why it's wrong here
Cat6a is copper, not fiber, and would require an RJ45 SFP, not an SR module.
✗
Coaxial cable
Why it's wrong here
Coaxial cable is used for cable internet, not for 10GBASE-SR fiber connections.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
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 220-1201 NAT questions on configuration and troubleshooting.
Common Networking Hardware — This question tests Common Networking Hardware — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Multimode fiber (OM3) — 10GBASE-SR is designed for multimode fiber (MMF) over short distances, typically up to 300 meters. Using single-mode fiber (SMF) would not work because the transceiver is optimized for multimode. The correct answer is multimode fiber (OM3 or OM4).
What should I do if I get this 220-1201 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 220-1201 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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