easyMultiple ChoiceObjective-mapped
200-901 Practice Question: An engineer needs to identify which hosts are…
An engineer needs to identify which hosts are reachable in a 10.0.0.0/24 network using an automated script that does not require any credentials on the target devices. Which protocol is best suited for this task?
⚠ Common exam trap
Cisco often tests the distinction between protocols that require credentials (SNMP) and those that do not (ICMP), and the trap here is that candidates may choose ARP thinking it can discover hosts without credentials, but ARP only works on the local subnet and does not confirm IP-level reachability across a routed network.
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
✓
ICMP
ICMP (Internet Control Message Protocol) is the correct choice because it provides the Echo Request and Echo Reply messages (commonly used by the 'ping' command) that can determine host reachability without requiring any authentication or credentials on the target devices. This makes ICMP ideal for an automated script that needs to probe a 10.0.0.0/24 network for live hosts, as it operates at the network layer and only requires IP connectivity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ICMP
Why this is correct
ICMP echo requests are unauthenticated and can be used to check reachability.
- ✗
CDP
Why it's wrong here
CDP is Cisco proprietary and requires the protocol to be enabled; also it does not verify reachability via ping.
- ✗
SNMP
Why it's wrong here
SNMP requires community strings for access, which are credentials.
- ✗
ARP
Why it's wrong here
ARP only resolves IP to MAC addresses within the same subnet; it does not work across routers.
Go deeper
Related to this question
About these practice questions
This 200-901 question is part of Courseiva's 989-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam 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 200-901 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.