CCNA Network Infrastructure and Connectivity Practice Question
Which cable type is commonly used to connect a switch to a router when using standard Ethernet interfaces on modern devices with auto-MDIX support?
⚠ Common exam trap
Remember that auto-MDIX allows for the use of straight-through cables in situations where crossover cables were once required.
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
✓
Straight-through Ethernet cable
A straight-through Ethernet cable is the common expected answer for switch-to-router Ethernet connections. On modern interfaces, auto-MDIX often makes crossover requirements less important in practice.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Rollover cable
Why it's wrong here
A rollover cable, also called a Cisco console cable, has a completely reversed pinout—pin 1 to pin 8, pin 2 to pin 7, and so on—and is used solely to connect a PC's COM or USB port to a device's console port for out-of-band administrative access. It carries asynchronous serial console signals, not Ethernet frames, and does not support data-plane communication between a switch and a router. While a rollover cable may plug into an RJ45-style console port, it is never inserted into a data Ethernet port.
When this WOULD be correct
If the exam question asked about connecting a console port of a router to a computer for configuration purposes, then a rollover cable would be the correct answer. This scenario focuses on terminal access rather than standard Ethernet connections.
- ✓
Straight-through Ethernet cable
Why this is correct
A straight-through Ethernet cable maps pins 1-8 identically on both ends, following TIA/EIA-568-B wiring, and is the standard for connecting unlike devices such as a switch to a router. Switches and routers use different transmit/receive pairs, so the straight-through pinout properly aligns the outbound pairs of one with the inbound pairs of the other. Even with Auto-MDIX on modern gear, the straight-through cable remains the expected and most commonly cited answer for this link.
- ✗
Serial DCE cable
Why it's wrong here
A serial DCE cable terminates a router's serial interface, using a V.35 or EIA/TIA-232 connector to connect to a CSU/DSU or a WAN service provider. The DCE side provides clocking timing, but this connection operates at Layer 1 over a serial WAN link, not over an Ethernet LAN. A switch's Ethernet port expects RJ45 copper or fiber with Ethernet framing, so a serial DCE cable cannot physically or logically connect a switch to a router in this context.
When this WOULD be correct
If the exam question asked about connecting a router to a console port of a switch for configuration purposes, specifically mentioning serial communication, then a serial DCE cable would be the correct answer.
- ✗
Fiber patch cable only
Why it's wrong here
Fiber patch cables are used in Ethernet links when both the switch and router have SFP or SFP+ optical transceivers, and they can support longer distances or higher bandwidth than copper UTP. However, saying 'fiber only' is incorrect because standard short-range LAN connections commonly use straight-through copper Cat5e/Cat6 cables. Fiber is selected for specific distance, bandwidth, or interference requirements, but it is not the default connection method, and a fiber patch cable alone is not required for a switch-to-router link.
When this WOULD be correct
In a question that asks about connecting devices over a fiber optic network, specifically mentioning the use of fiber optic interfaces or when discussing long-distance connections between network devices, a fiber patch cable would be the correct answer.
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.
✓Straight-through Ethernet cableCorrect answer▾
Why this is correct
A straight-through Ethernet cable maps pins 1-8 identically on both ends, following TIA/EIA-568-B wiring, and is the standard for connecting unlike devices such as a switch to a router. Switches and routers use different transmit/receive pairs, so the straight-through pinout properly aligns the outbound pairs of one with the inbound pairs of the other. Even with Auto-MDIX on modern gear, the straight-through cable remains the expected and most commonly cited answer for this link.
✗Rollover cableWrong answer — click to see why▾
Why this is wrong here
A rollover cable is used to connect a console port of a router or switch to a computer terminal, not for connecting switches to routers over Ethernet interfaces. In modern networking setups with auto-MDIX, a straight-through cable is the standard choice.
★ When this WOULD be the correct answer
If the exam question asked about connecting a console port of a router to a computer for configuration purposes, then a rollover cable would be the correct answer. This scenario focuses on terminal access rather than standard Ethernet connections.
Why candidates choose this
Candidates may confuse the rollover cable with other types of cables due to its use in networking, leading them to mistakenly think it could be applicable in various connection scenarios, especially if they have limited hands-on experience.
✗Serial DCE cableWrong answer — click to see why▾
Why this is wrong here
A serial DCE cable is used for connecting devices in a serial communication setup, typically for console access or point-to-point connections, not for standard Ethernet interfaces between a switch and a router.
★ When this WOULD be the correct answer
If the exam question asked about connecting a router to a console port of a switch for configuration purposes, specifically mentioning serial communication, then a serial DCE cable would be the correct answer.
Why candidates choose this
Candidates may choose this option due to familiarity with various cable types and their uses in networking, leading them to mistakenly associate serial cables with device connections in a broader context.
✗Fiber patch cable onlyWrong answer — click to see why▾
Why this is wrong here
A fiber patch cable is not used to connect a switch to a router over standard Ethernet interfaces, as it requires compatible fiber optic ports and transceivers. Ethernet interfaces typically use copper cabling, such as straight-through cables, for such connections.
★ When this WOULD be the correct answer
In a question that asks about connecting devices over a fiber optic network, specifically mentioning the use of fiber optic interfaces or when discussing long-distance connections between network devices, a fiber patch cable would be the correct answer.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of network connections, thinking that fiber optics are superior for all types of connections, or because they recall fiber cables being used in networking scenarios without considering the specific context of Ethernet interfaces.
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?”
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
Related to this question
Learn chapter
Ethernet Standards
Key term
Switch
A switch is a networking device that connects devices on a local area network and uses MAC addresses to forward data only to the intended recipient.
Key term
Medium Dependent Interface Crossover
A Medium Dependent Interface Crossover (MDIX) is a special Ethernet cable that swaps the transmit and receive wire pairs so two similar devices can connect directly without a switch or hub.
About these practice questions
Courseiva writes every 200-301 question from scratch — 1,389 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.