The answer is that a firewall on the target host blocking the probe’s port is the most likely cause of the 'Connection refused' error in MID Server discovery logs. This error occurs because the target’s firewall actively sends a TCP RST packet to reject the connection attempt, rather than simply dropping the traffic, which distinguishes it from a timeout or unreachable host scenario. On the ServiceNow Certified Application Developer CAD exam, this question tests your ability to differentiate between network-layer errors—specifically, that 'Connection refused' points to a port-level block, not authentication or routing issues. A common trap is confusing this with incorrect credentials, but those would produce an authentication failure, not a TCP-level rejection. Remember the memory tip: 'Refused means the door is locked, not that you have the wrong key'—firewalls refuse, credentials fail.
SNOW-CAD Platform Features and Integration Practice Question
This SNOW-CAD practice question tests your understanding of platform features and integration. 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.
A company is using a MID Server to run a discovery probe. The probe fails with a timeout error. The developer checks the MID Server logs and sees 'Connection refused'. What is the most likely issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The target host's firewall is blocking the port used by the probe.
The 'Connection refused' error in the MID Server logs indicates that the target host actively rejected the connection attempt on the specified port. This is most commonly caused by a firewall on the target host blocking the port used by the discovery probe, as the firewall sends a TCP RST packet to refuse the connection. Incorrect credentials would result in an authentication failure, not a connection refusal, and an unreachable host would produce a 'No route to host' or timeout error.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The MID Server credentials are incorrect.
Why it's wrong here
Incorrect credentials would lead to authentication failure, not connection refused.
✗
The MID Server's SSL certificate is expired.
Why it's wrong here
SSL certificate issues occur after connection is established, not at the TCP level.
✓
The target host's firewall is blocking the port used by the probe.
Why this is correct
Connection refused indicates the TCP connection was rejected, often due to firewall or service not running.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The target host is unreachable from the MID Server network.
Why it's wrong here
Unreachable would show 'No route to host' or similar.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'Connection refused' with 'Host unreachable' or 'Timeout', but Cisco tests the distinction that a firewall actively blocking a port sends a TCP RST (refused), while a network-level block or host down results in a timeout or ICMP unreachable.
Trap categories for this question
Similar concept trap
Unreachable would show 'No route to host' or similar.
Command / output trap
Unreachable would show 'No route to host' or similar.
Detailed technical explanation
How to think about this question
The 'Connection refused' error occurs when the MID Server sends a TCP SYN packet to the target host's IP and port, and the target responds with a TCP RST (Reset) packet, typically because no service is listening on that port or a firewall rule explicitly drops the SYN and sends a RST. In ServiceNow discovery, probes often use specific ports (e.g., 22 for SSH, 5985/5986 for WinRM, 161 for SNMP), and a firewall rule that denies inbound traffic on that port will trigger this behavior. A real-world scenario is when a security group or iptables rule on the target host blocks the probe port but allows ICMP, making the host pingable but still refusing the probe connection.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the SNOW-CAD exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Platform Features and Integration — This question tests Platform Features and Integration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The target host's firewall is blocking the port used by the probe. — The 'Connection refused' error in the MID Server logs indicates that the target host actively rejected the connection attempt on the specified port. This is most commonly caused by a firewall on the target host blocking the port used by the discovery probe, as the firewall sends a TCP RST packet to refuse the connection. Incorrect credentials would result in an authentication failure, not a connection refusal, and an unreachable host would produce a 'No route to host' or timeout error.
What should I do if I get this SNOW-CAD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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