200-201 Security Concepts Practice Question
During an incident, an analyst finds a workstation that is beaconing to an external IP every 60 seconds using DNS TXT queries. The queries contain long, base64-encoded subdomains. The endpoint has no other suspicious network connections. Which technique is most likely being used?
⚠ Common exam trap
The trap here is treating any suspicious DNS activity as a DGA, when the encoded TXT payloads and steady beaconing point specifically to tunneling.
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
✓
DNS tunneling for command-and-control
The combination of regular beaconing, TXT record use, and base64-encoded subdomains strongly indicates DNS tunneling for command-and-control. Attackers use DNS because it is widely allowed through firewalls and rarely inspected deeply. Detecting it requires monitoring for anomalous query volume, unusually long labels, and consistent timing to a single external resolver.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Domain generation algorithm for ransomware
Why it's wrong here
A domain generation algorithm produces many pseudorandom domain names that malware tries to resolve to find its controller. While it uses DNS, it typically generates a high volume of failed lookups to varying domains, not consistent TXT queries to one external IP with encoded subdomains. The steady beaconing pattern here indicates tunneling, not DGA.
- ✗
Fast flux DNS for phishing
Why it's wrong here
Fast flux rapidly changes the IP addresses associated with a domain to evade takedown and tracking. It would appear as many different A records for a single domain over time, not repeated TXT queries with encoded payloads to a stable external IP. The encoded subdomains point to data transfer, not IP rotation.
- ✓
DNS tunneling for command-and-control
Why this is correct
DNS tunneling encodes data in DNS queries and responses, often using TXT records and long encoded subdomains, to exfiltrate data or receive commands. The regular 60-second beaconing and base64 payloads in TXT queries are hallmarks of DNS-based command-and-control, which blends with legitimate DNS traffic and often bypasses egress filtering.
- ✗
DNS cache poisoning for redirection
Why it's wrong here
DNS cache poisoning inserts false records into a resolver's cache to redirect users to malicious sites. It is an attack on the resolver, not a beaconing pattern from an endpoint. The periodic TXT queries with base64 content indicate an active tunnel for command-and-control, not cache manipulation.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 200-201 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 200-201 exam.