Question 1hardmultiple choice
Full question →Based on the exhibit, what is the MOST likely explanation for the network traffic?
The affected host is not showing a large amount of internet-bound traffic, but its DNS behavior is highly unusual.
hardmultiple choiceObjective-mapped
Exhibit
DNS query log excerpt: Host: CORP-LT-17 16:18:02 a9f3d1k2d.update-check.com A NXDOMAIN 16:18:03 b7p9q2s1n.update-check.com A NXDOMAIN 16:18:04 k8z1m4c7r.update-check.com A NXDOMAIN 16:18:05 u3n6t9x0v.update-check.com A NXDOMAIN 16:18:06 9q2m7a4p1.update-check.com A NXDOMAIN Proxy log excerpt: No corresponding HTTP or HTTPS sessions observed TTL observed: 60 seconds on all queries
Based on the exhibit, what is the MOST likely explanation for the network traffic?
The affected host is not showing a large amount of internet-bound traffic, but its DNS behavior is highly unusual.
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
DNS tunneling used for command-and-control or data transfer
The long random-looking subdomains, repeated NXDOMAIN responses, and lack of normal web traffic are consistent with malicious DNS-based communication.
B
Distractor review
ARP poisoning causing the host to redirect traffic to a rogue gateway
ARP poisoning would mainly affect local layer-2 behavior, not produce repeated suspicious DNS subdomain lookups with NXDOMAIN responses.
C
Distractor review
A browser cache synchronization feature repeatedly polling a cloud service
Legitimate synchronization usually generates consistent service traffic and valid endpoints, not random-looking subdomains and repeated failures.
D
Distractor review
A misconfigured static route sending all web traffic to the wrong subnet
A routing error would affect broader connectivity, but it would not specifically create this distinctive DNS query pattern.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A laptop is suspected of being used in a malware incident. It is still powered on and connected to Wi-Fi. What should the responder do before shutting it down?
Question 2
An employee reports a ransomware note on a file server. The server is still powered on, shares are still being accessed, and management wants service restored as quickly as possible. What should the incident response team do first?
Question 3
An employee reports a ransomware note on a finance laptop. The laptop is still powered on, connected to Wi-Fi, and the user says they were just working in a spreadsheet. Management wants the fastest safe response that also preserves evidence. What should the responder do first?
Question 4
You are handed a company laptop suspected in an insider theft case. Legal says the evidence may be needed in court. Which action best preserves admissibility?
Question 5
A developer wants to reduce the risk of SQL injection in a new customer search form. Which two changes are the best mitigations? Select two.
Question 6
A branch office uses a flat LAN, and a compromise on one user workstation could spread quickly to finance systems. Management wants finance workstations isolated from general users, but finance staff still need access to a central finance application and network printer. What is the best design change?
FAQ
Questions learners often ask
What does this SY0-701 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: DNS tunneling used for command-and-control or data transfer — The pattern is highly consistent with DNS tunneling or a DNS-based command-and-control channel. The subdomains are long and randomized, the requests mostly fail with NXDOMAIN, and there is no corresponding HTTP or HTTPS activity. Attackers often use DNS this way because it is widely allowed out of networks and can bypass traditional web filtering. The low TTL and repetitive structure further suggest automated beaconing rather than normal application behavior. Why others are wrong: ARP poisoning is a layer-2 attack and would not explain the specific DNS query pattern. A cloud sync client would normally contact known service endpoints and generate successful lookups, not repeated random subdomain failures. A bad static route could break connectivity, but it would not create a stream of structured DNS requests that look like encoded data or command traffic.
What should I do if I get this SY0-701 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
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