Question 1

Select the iptables option that specifies the destination address of packets for a rule:

Accepted Answer

The option "-d" in iptables is used to specify the destination address of packets for a rule.

Question 2

Which command can be used to see what network services are running on your network?

Accepted Answer

nmap is a network scanning tool that can be used to discover devices and services on a network.

Question 3

What utility in the sysstat package measures the flow of information to and from disk devices?​

Accepted Answer

iostat is the utility in the sysstat package that measures the flow of information to and from disk devices, providing statistics on input/output for devices and partitions.

Question 4

Older hardware that is malfunctioning may begin to send large amounts of information to the CPU when not in use. What is this process called?​

Accepted Answer

Jabbering refers to a malfunction in network devices, including older hardware, where they start sending excessive and unnecessary data to the CPU or network, often due to a fault or error in the hardware.

Question 5

How often are sar commands scheduled to run on both Fedora 20 and Ubuntu Server 14.04?

Accepted Answer

The sar command is typically scheduled to run every ten minutes by default on both Fedora 20 and Ubuntu Server 14.04, as part of the sysstat package that collects and reports system activity information. This frequency is defined in the cron job configuration for sysstat.

Question 6

What option can be specified with the rpm command to identify any missing files in a package or package dependency?

Accepted Answer

The -V option with the rpm command is used to verify a package, which includes checking for missing files among other verifications.

Question 7

Performance problems are caused by hardware, not software.

Accepted Answer

Performance problems can be caused by both hardware and software issues, including inadequate hardware resources, software bugs, inefficient code, or compatibility issues.

Question 8

Performing regular system backups and identifying potential problem areas are examples of reactive maintenance.

Accepted Answer

These actions are examples of proactive maintenance, as they are performed to prevent problems before they occur, rather than responding to them after they happen.

Question 9

Almost all hardware problems are the result of damaged hardware.

Accepted Answer

While damaged hardware can cause problems, many hardware issues also stem from software conflicts, driver issues, firmware updates, overheating, and other non-damage related causes.

Question 10

What is the most common hardware component to fail on a Linux system?

Accepted Answer

Hard disks are the most common hardware component to fail on a Linux system due to their mechanical parts and constant use, leading to wear and tear over time.

Question 11

If the / filesystem becomes corrupted, the system is unstable and must be turned off.

Accepted Answer

If the root (/) filesystem becomes corrupted, it can lead to system instability, crashes, or inability to boot, necessitating a shutdown to prevent further damage and to repair the filesystem.

Question 12

By default, the shell on a Linux system limits the number of filehandles a program can have open to what value?

Accepted Answer

The default limit for the number of file handles a program can have open in a Linux system is typically 1024. This value can be viewed and adjusted using the `ulimit` command.

Question 13

What file contains the DSA public key in the /etc/ssh directory?

Accepted Answer

The file with the extension `.pub` in the /etc/ssh directory, such as `ssh_host_dsa_key.pub`, contains the DSA public key. Public key files are used to authenticate to clients connecting to the server.

Question 14

Select the option that, when used with the sar command, displays swap statistics:

Accepted Answer

The -B option with the sar command is used to display paging statistics, which include swap space usage details.

Question 15

What option for the iptables command can be used to specify the default policy for a certain chain type?

Accepted Answer

The -P option for the iptables command is used to specify the default policy (such as ACCEPT, DROP, or REJECT) for a certain chain (INPUT, FORWARD, or OUTPUT).

Question 16

Running background processes using what command allows you to exit your command-line shell without ending any background processes?

Accepted Answer

The command `nohup` allows you to run commands or shell scripts in the background even after logging out from the shell session. It stands for 'no hang up', and it prevents the process from being terminated when the terminal closes.

Question 17

If applications run into difficulties gaining resources during execution and stop functioning, restarting the process using a specific kill signal may resolve the issue. Select the proper kill signal below:

Accepted Answer

SIGHUP is often used to restart processes by signaling them to re-read their configuration files or settings. It's a way to refresh an application without completely stopping it, which can be useful for resolving resource allocation issues without a full shutdown.

Question 18

If network services that are started by inetd or xinetd are in use, what can be used to provide extra security?

Accepted Answer

TCP wrappers can provide additional security by allowing or denying access to network services based on IP addresses or domain names. This is particularly useful for services started by inetd or xinetd, as it adds an extra layer of access control.

Question 19

Which sar command option is used to display statistics for the processor queue?

Accepted Answer

The sar command option '-q' is used to display statistics for the processor queue, showing the load on the system.

Question 20

If some users, such as software developers, need to run certain commands as the root user in certain situations, it is best to allow them to log on to the root user account via the su command.

Accepted Answer

It is more secure to use the sudo command, which allows users to run specific commands as the root user without needing to log in as root, providing an audit trail and limiting access to root privileges.

Quiz 14: Troubleshooting, Performance, and Security