hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A company uses a proxy server for internet access
A company uses a proxy server for internet access. Users report that they can access internal websites but cannot reach external sites. The proxy server's IP is configured in the browser settings. Which network service is most likely failing?
⚠ Common exam trap
CompTIA often tests the distinction between a proxy server failure and a DNS failure, where candidates mistakenly think DNS is the issue because external sites fail, but the key clue is that internal sites are accessible, which would not be the case if DNS were broken.
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
✓
Proxy server
The proxy server is configured in the browser settings, but users can reach internal websites (which bypass the proxy) while failing to reach external sites (which require the proxy). This indicates the proxy server itself is not functioning or unreachable, as it is the designated intermediary for external traffic. DNS, DHCP, and NAT would affect both internal and external access if they were failing, so the proxy server is the most likely culprit.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DNS
Why it's wrong here
Since users can access internal websites, the internal DNS resolution is functioning correctly, indicating that local name resolution is not the issue. While external DNS resolution could theoretically be failing, in a setup utilizing a proxy server, the proxy typically handles all outbound DNS queries on behalf of the client. Therefore, if external sites are unreachable, the problem points more directly to the proxy server's operation rather than a general DNS failure on the client or internal DNS server.
- ✗
DHCP
Why it's wrong here
DHCP (Dynamic Host Configuration Protocol) is responsible for automatically assigning IP addresses, subnet masks, default gateways, and DNS server information to client devices. The ability of users to access internal network resources confirms that their devices have successfully obtained valid IP configurations from the DHCP server. If DHCP were failing, users would likely not have network connectivity at all, including to internal sites, making it an unlikely cause for only external access issues.
- ✓
Proxy server
Why this is correct
A proxy server acts as an intermediary for requests from clients seeking resources from other servers, particularly for internet access. When a company uses a proxy for internet access, all outbound requests to external websites are explicitly routed through it. If the proxy server is offline, misconfigured, or experiencing issues, it will fail to forward these external requests, preventing users from reaching the internet while their ability to access internal network resources remains unimpaired. This specific symptom directly points to the proxy as the single point of failure for external connectivity.
- ✗
NAT
Why it's wrong here
Network Address Translation (NAT) is a method of remapping one IP address space into another, commonly used by routers to allow multiple devices on a private network to share a single public IP address for internet access. While a proxy server might utilize NAT internally for its own outbound connections, the primary function of NAT is usually at the network perimeter (router). If NAT were failing at the router level, it would typically prevent all external connectivity for the entire network, potentially even affecting how the proxy itself communicates externally, but the symptom of *only* external access failing while internal access works points away from a general NAT failure.
Visual reference
Go deeper
Related to this question
Learn chapter
Network Configuration: IP, DNS, DHCP
Key term
NAT
NAT (Network Address Translation) is a method that allows multiple devices on a private network to share a single public IP address when accessing the internet.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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