XK0-004 · Question #262
An administrator notices a website hosted on an httpd web server is not loading. Upon further inspection, the administrator learns there are no httpd processes running. When starting the service, the
The correct answer is D. The out-of-memory killer was activated due to low available memory, causing the kernel to kill the. The Linux OOM (Out-of-Memory) killer terminates processes when system memory is critically low, which explains why httpd starts successfully but disappears after a few minutes.
Question
An administrator notices a website hosted on an httpd web server is not loading. Upon further inspection, the administrator learns there are no httpd processes running. When starting the service, the site operates correctly for a few minutes before the process disappears again. Which of the following should the administrator consider as the MOST likely possibility before troubleshooting the issue?
Options
- AThe CPU has too much load, causing it to overheat, and the kernel is automatically killing the
- BAn external database to which the web server connects is offline, causing httpd to die due to
- CShared libraries, which were recently updated, are causing compatibility issues and httpd to die
- DThe out-of-memory killer was activated due to low available memory, causing the kernel to kill the
- EThe server is intermittently losing access to the network, causing socket errors that trigger httpd
How the community answered
(63 responses)- A10% (6)
- B3% (2)
- C2% (1)
- D84% (53)
- E2% (1)
Why each option
The Linux OOM (Out-of-Memory) killer terminates processes when system memory is critically low, which explains why httpd starts successfully but disappears after a few minutes.
CPU overheating would trigger thermal throttling or a system-wide shutdown, not selectively terminate a single httpd process.
A missing external database would cause httpd to log connection errors and return failures to clients, but would not cause the httpd process itself to exit.
Shared library compatibility issues would cause httpd to crash immediately on startup rather than allowing it to run successfully for several minutes first.
The Linux kernel's OOM killer is designed to terminate one or more processes when available memory is exhausted to prevent a total system crash. The pattern of httpd starting and running briefly before disappearing is a classic symptom - the process runs until memory pressure triggers the OOM killer, which selects and kills processes based on a scoring algorithm. Evidence of this can be confirmed in /var/log/messages or via dmesg output showing 'Out of memory: Kill process'.
Intermittent network loss causes socket errors and failed requests that are handled internally by httpd, and does not cause the process to terminate.
Concept tested: Linux OOM killer process termination behavior
Source: https://www.kernel.org/doc/html/latest/admin-guide/mm/oom_kill.html
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