- A
Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'.
This is correct because CDP must be enabled globally with 'cdp run' and then on the specific interface with 'cdp enable'. Both commands are required for CDP to operate on an interface.
- B
Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp run'.
Why wrong: This is incorrect because 'cdp enable' is an interface-level command, not a global command. The correct global command is 'cdp run'.
- C
Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.
Why wrong: This is incorrect because there is no 'no cdp disable' command. The correct command to enable CDP on an interface is 'cdp enable'.
- D
Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.
Why wrong: This is incorrect because both commands are wrong: 'cdp enable' is not a global command, and 'no cdp disable' is not a valid command.
Enabling CDP Globally and on Interfaces for Neighbor Discovery
This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are connected to the console of R1. The network administrator reports that R1 cannot discover neighboring devices via CDP. R1 is connected to SW1 via GigabitEthernet0/0. You suspect CDP is disabled globally or on the interface. Your task is to enable CDP and verify neighbor discovery.
Quick Answer
The answer is to enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'. This is correct because CDP operates at Layer 2 and is disabled by default on newer Cisco IOS versions for security reasons; the global command 'cdp run' activates the protocol on the router, while 'cdp enable' on the specific interface allows that port to send and receive CDP advertisements. On the CCNA 200-301 v2 exam, this scenario tests your understanding of the two-level CDP configuration hierarchy—global and interface—and the common trap is assuming that enabling CDP globally automatically enables it on all interfaces, which is false; you must explicitly enable it per interface. A reliable memory tip is to think of CDP as a light switch: 'cdp run' turns the power on for the whole house, but 'cdp enable' flips the switch for the individual room.
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
Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'.
CDP was disabled globally and on the interface. Enabling CDP globally and then on the interface allows R1 to discover directly connected Cisco devices.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'.
Why this is correct
This is correct because CDP must be enabled globally with 'cdp run' and then on the specific interface with 'cdp enable'. Both commands are required for CDP to operate on an interface.
Related concept
Authentication checks who the user is.
- ✗
Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp run'.
Why it's wrong here
This is incorrect because 'cdp enable' is an interface-level command, not a global command. The correct global command is 'cdp run'.
- ✗
Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.
Why it's wrong here
This is incorrect because there is no 'no cdp disable' command. The correct command to enable CDP on an interface is 'cdp enable'.
- ✗
Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.
Why it's wrong here
This is incorrect because both commands are wrong: 'cdp enable' is not a global command, and 'no cdp disable' is not a valid command.
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.
✓Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'.Correct answer▾
Why this is correct
This is correct because CDP must be enabled globally with 'cdp run' and then on the specific interface with 'cdp enable'. Both commands are required for CDP to operate on an interface.
✗Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp run'.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that 'cdp enable' is used on interfaces, not globally. The global command to enable CDP is 'cdp run'.
Why candidates choose this
Candidates might confuse the global and interface commands, thinking 'cdp enable' works globally because it sounds like it enables CDP.
✗Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that 'no cdp disable' is not a valid Cisco IOS command. The proper command is 'cdp enable'.
Why candidates choose this
Candidates might think that since CDP can be disabled per interface with 'cdp disable', using 'no cdp disable' would re-enable it, but that command does not exist.
✗Enter global configuration mode, issue 'cdp enable', then enter interface configuration mode for GigabitEthernet0/0 and issue 'no cdp disable'.Wrong answer — click to see why▾
Why this is wrong here
The specific factual errors are: the global command should be 'cdp run', and the interface command should be 'cdp enable'.
Why candidates choose this
Candidates might combine two common misconceptions: confusing global and interface commands, and thinking 'no cdp disable' is valid.
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: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Trap categories for this question
Command / output trap
This is incorrect because 'cdp enable' is an interface-level command, not a global command. The correct global command is 'cdp run'.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Enter global configuration mode, issue 'cdp run', then enter interface configuration mode for GigabitEthernet0/0 and issue 'cdp enable'. — CDP was disabled globally and on the interface. Enabling CDP globally and then on the interface allows R1 to discover directly connected Cisco devices.
What should I do if I get this 200-301 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are connected to the console of SW1. The network administrator reports that SW1 cannot discover neighbouring devices using CDP. SW1 is connected to R1 via GigabitEthernet0/1. CDP is globally enabled, but still no neighbours are shown.
medium- ✓ A.Enable CDP on interface GigabitEthernet0/1 with the command 'cdp enable'.
- B.Enable CDP globally with the command 'cdp run'.
- C.Use the command 'lldp run' to enable LLDP as an alternative.
- D.Check the physical cable and interface status on GigabitEthernet0/1.
Why A: CDP was globally enabled but the interface GigabitEthernet0/1 had CDP disabled by default (or was explicitly disabled). Enabling CDP on the interface allowed neighbour discovery.
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Last reviewed: Jun 7, 2026
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