Red Hat Linux Interview Series 10

[Chetan_Tiwary_]

Q.) Explain the below situation  and what steps you will take here  :

[ 7283.479871] Out of memory: Kill process 15665 (main.out) score 565 or sacrifice child
[ 7283.479879] Killed process 15665 (main.out) total-vm:67111332kB, anon-rss:92kB, file-rss:4kB, shmem-rss:30080832kB
[ 7283.479951] oom_reaper: reaped process 15665 (main.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:30080832kB

is it necessarily an issue ?

Q.) I need to add a secondary IP to the interface ens1, how can I do it ?

Q.) Explain the http error code in the below screenshot and what will your approach to resolve this :

I'll be posting a series of Linux-related questions covering various skill levels. Feel free to share your insights and expertise. Your contributions will benefit learners at all stages, from those in current roles to those preparing for Linux interviews.

[Trevor]

Explain the http error code in the below screenshot and what will your approach to resolve this.

Well, the good news is that there's a chance I can resolve the issue since the attempt
to connect to the service is on the same host that the connection is being attempted
from.

Okay, let's begin with the log-hanging fruit: What is that error?
The HTTP 503 Service Unavailable server error response status code indicates that the server is not ready to handle the request.

HTTP error 503 signifies that the website is online and running, but can’t be reached at the present moment.

Some common causes are:
- the server (not the service) is down for maintenance
- the server (not the service) is overloaded.
- plugins issue

How will I approach the resolution?  I'll begin with those all important log files - they
are a diamond mine in times of troubleshooting!!!

If my HTTP service is either Apache Nginx, I'm going to check the following:

• Apache: /var/log/apache2/error.log
• Nginx: /var/log/nginx/error.log

Even before checking my log files, I would just restart my HTTP service.  That's a
quick and dirty procedure.  I just might save myself an hour or two of troubleshooting
time!  It certainly can't hurt to restart the service, because I'm not able to display a
webpage anyway.

Also, maybe there is a service, or some services, that are hogging the CPU, and
not allowing the HTTP service to get a turn.  Well, pick your tool of choice to take 
a look at the process load on the system.

After attempting those first two easy steps, go dig into the log files.  They truly are
a treasure trove of information!!!

Okay, that will conclude my comments for this episode of "What's the Problem?"

[Trevor]

Adding a secondary IP address to the interface ens1 can be accomplished via either of the following methods:

1)    #  ip addr add   IP-Address/subnet-mask   dev  ens1  

2)    #  nmcli con mod ens1   +ipv4.addresses  IP-Address/subnet-mask

View the secondary using either of the following commands:

1)   #  ip a s

               or

2)   # nmcli device show