Refer to the Exhibit Practice Questions

The ambient temperature sensor in the data center is reporting incorrectly and the actual temperature is higher.

Why wrong: Handheld thermometer confirms 20°C; other servers in same rack are fine, so ambient is normal.

The internal fans are not operating at full speed due to a failed fan controller.

Why wrong: Fans are verified spinning, and a fan controller failure would likely cause constant overheating or sensor errors, not just peak hours.

The file server's power supply is failing and causing voltage drops that affect fan performance.

Why wrong: A failing PSU typically causes power-related errors or system instability, not specific CPU thermal events; fans are verified operational.

The CPU heatsink is not properly installed.

Why wrong: While this could cause overheating, the system would still detect a fan if it were connected. The error specifically mentions no fan detection.

The BIOS fan profile is set to 'Silent' mode.

Why wrong: A silent profile might stop the fan under light load, but the BIOS would still detect its presence during POST. 'No fan detected' indicates an electrical disconnection.

The CPU has failed.

Why wrong: A CPU failure would typically result in no POST or a different beep code, not a fan-specific error message.

Delete log files in /var/log.

Why wrong: While it frees space, it might not free enough, and removing logs hampers troubleshooting and auditing.

Resize /dev/sda1 to 30G.

Why wrong: Resizing requires unmounting or rebooting and is not a quick solution; also, the root partition may be LVM-based or not easily extended online.

Change the RAID level of /dev/sda.

Why wrong: RAID level changes are unrelated to free space management and could introduce additional I/O load or data loss risk.

The server's default gateway is incorrect

Why wrong: A gateway misconfiguration would affect all outbound traffic, but the firewall rules are the direct cause of blocking inbound port 80.

SELinux is enforcing and blocking port 80

Why wrong: While SELinux can block ports, the explicit iptables output directly shows a REJECT all rule that denies port 80 traffic.

The web server is not bound to the correct IP address

Why wrong: The web server is confirmed running; if it were misbound, local tests would fail, but the issue is external connectivity blocked by the firewall.

Memory leak in an application

Why wrong: Incorrect. While a memory leak could cause high usage, the exhibit does not indicate a specific application; the most direct interpretation is insufficient memory.

Virtual memory is misconfigured

Why wrong: Incorrect. Virtual memory settings appear normal; the issue is lack of physical memory, not a configuration problem.

Page file is too small

Why wrong: Incorrect. The page file size (16,384 MB) is equal to physical memory; that is typically sufficient.

Check for failure of the liquid cooling system for CPU1.

Why wrong: Most servers use air cooling; liquid cooling is uncommon and would require verification, but it's not the first step without other evidence.

Replace CPU1 because the high temperature indicates an internal short.

Why wrong: A CPU that overheats is rarely faulty; almost always it's a cooling issue. Internal shorts would result in immediate failure, not gradual temperature increase.

Install additional high-speed fans to increase static pressure.

Why wrong: Adding fans may help but does not fix the underlying airflow path problem; it also may not be possible in a 1U/2U chassis.

The hard drive data cable is loose

Why wrong: A loose cable would often result in the drive not being detected at all, not just a boot error. The error specifically mentions hard disk (3F0), suggesting it is detected.

The boot sector is corrupted

Why wrong: A corrupt boot sector typically produces an error like 'Missing operating system' rather than 'Boot device not found'.

The hard drive has failed

Why wrong: A failed drive would typically not be listed as 'Hard Disk: (3F0)'; that identifier suggests the drive is recognized but not bootable.

The Nginx service is not running.

Why wrong: If Nginx were down, it would not log this error; the reverse proxy must be operational to generate the entry.

The firewall on the reverse proxy is blocking port 80.

Why wrong: A firewall block would typically result in a timeout, not an immediate connection refusal from the upstream server.

The client's DNS cannot resolve example.com.

Why wrong: The error occurs at the backend connection level, long after client DNS resolution has succeeded.

The last DROP rule blocks all traffic, including established SSH sessions.

Why wrong: The last DROP rule blocks traffic, but the earlier ACCEPT for RELATED,ESTABLISHED allows return packets of existing connections, so this does not explain new SSH failure.

The default INPUT policy is set to ACCEPT, allowing all traffic.

Why wrong: A default ACCEPT policy does not override an earlier DROP rule; the DROP for SSH still takes effect.

The ACCEPT rule for port 22 is missing the ESTABLISHED state, preventing return traffic.

Why wrong: The ACCEPT rule uses state NEW, which is fine; the RELATED,ESTABLISHED rule permits return traffic. The problem is the order.

Run a full backup and then replace the drive

Why wrong: While backups are vital, the immediate priority is to replace the failing drive to maintain array redundancy.

Rebuild the array to include the hot spare

Why wrong: A hot spare is only automatically integrated upon actual drive failure; you cannot force a rebuild using a hot spare for a drive that is still present but predicting failure.

Continue monitoring; the drive is still functional

Why wrong: The predictive failure indicates imminent failure; waiting could lead to data loss or extended downtime.

Tune the database engine's query cache size.

Why wrong: Query cache tuning can help in specific scenarios, but the overwhelming evidence of swapping points to a systemic memory shortage that tuning cannot fully overcome.

Configure the server to use a larger swap partition.

Why wrong: Enlarging swap would encourage more swapping, severely degrading performance; it's a stopgap, not a solution.

Replace the existing hard drives with faster SSDs.

Why wrong: SSDs would reduce I/O latency, but the high swapping indicates insufficient RAM; SSDs alone won't eliminate frequent disk-based reads due to low memory.

The DNS server's root hints are misconfigured.

Why wrong: Root hints are used when the server needs to forward queries for external domains; for its own zone it answers authoritatively.

The DNS server is not configured to forward queries to an external DNS server.

Why wrong: The server is authoritative for contoso.com, so forwarding is not needed for records within its own zone.

The DNS server has an incorrect reverse lookup zone configuration.

Why wrong: Reverse lookup zones map IP addresses to names; this query is for a name to IP, so reverse zone configuration is not involved.

Enable XMP profile in the BIOS to force all DIMMs to 2666 MT/s.

Why wrong: XMP (Extreme Memory Profile) is an overclocking feature typically unavailable or unsuitable for stable server operations with registered memory.

Clear the CMOS to reset the memory training data.

Why wrong: Clearing CMOS might trigger retraining but will not override the hardware limitation imposed by the 2133 MT/s DIMM.

Move the DIMM from A1 to A2 and the DIMM from A2 to A1.

Why wrong: Swapping slots does not eliminate the speed mismatch; the slowest DIMM still dictates the memory bus speed.

RAID controller

Why wrong: RAID controller issues might present as disk array failures or rebuild logs, not specific medium errors on a single drive.

RAM module

Why wrong: Faulty RAM typically causes memory parity errors or kernel panics, not I/O errors with sense key reporting.

Power supply

Why wrong: Power supply failures often generate power-related log entries (e.g., voltage warnings), not disk I/O errors.

The INPUT policy is set to ACCEPT.

Why wrong: Although the default policy is ACCEPT, the explicit DROP rule at the end of the chain overrides it for all packets not matching earlier rules.

The NAS device uses a different subnet.

Why wrong: Subnet addressing is a network configuration issue, not a local firewall rule; the firewall is dropping packets regardless of source/destination subnet.

The SSH ACCEPT rule is allowing traffic.

Why wrong: The SSH rule correctly permits port 22 traffic but does not interfere with port 10000 traffic.