LPIC-1 Essential System Services and Networking Practice Test 3 — 15 Questions

Question 1

A web server running on this host is not accessible from clients. Based on the exhibit, what is the most likely reason?

Accepted Answer

Incoming HTTP traffic is blocked by a DROP rule on port 80.. The exhibit shows a firewall rule set where the INPUT chain has a DROP rule for destination port 80 (HTTP). Since incoming HTTP traffic from clients must traverse the INPUT chain to reach the local web server process, this DROP rule explicitly blocks all inbound HTTP requests, making the web server inaccessible. The FORWARD chain is irrelevant because traffic destined for the local host uses the INPUT chain, not FORWARD.

Answer

The FORWARD chain policy is DROP.

Answer

The OUTPUT chain policy is ACCEPT.

Answer

SSH traffic is blocked.

Question 2

Based on the exhibit, what is the most likely cause of the SSH service failure?

Accepted Answer

Another service is already listening on port 22.. The exhibit shows that the sshd service failed to start because the address (0.0.0.0:22) is already in use. This indicates that another process is already bound to port 22, preventing sshd from binding to it. Therefore, the most likely cause is that another service is already listening on port 22.

Answer

The sshd service is disabled.

Answer

The firewall is blocking port 22.

Answer

The SSH configuration file has a syntax error.

Question 3

An administrator notices that SSH connections to a remote Linux server are timing out. After confirming network connectivity, which command should the administrator run on the server to check whether the SSH daemon is actively listening?

Accepted Answer

systemctl status sshd. The `systemctl status sshd` command checks the status of the SSH daemon service managed by systemd, directly reporting whether it is active (running) or inactive (stopped). This is the most straightforward way to verify that the SSH daemon is actively listening, as it queries the service manager rather than relying on network-level probing.

Answer

ls /etc/ssh/

Answer

nc -zv localhost 22

Answer

netstat -tuln

Question 4

A system administrator wants to configure NTP client on a server running systemd and using systemd-timesyncd. Which file should be edited to set the NTP server?

Accepted Answer

/etc/systemd/timesyncd.conf. On a system using systemd-timesyncd, the NTP server configuration is stored in /etc/systemd/timesyncd.conf. This file is read by the systemd-timesyncd service to determine which NTP servers to synchronize with. Editing this file is the correct method for configuring NTP clients under systemd.

Answer

/etc/chrony.conf

Answer

/etc/ntp.conf

Answer

/etc/ntp/ntp.conf

Question 5

A Linux system's hostname resolution does not consult /etc/hosts before querying DNS. Which file controls the order of name resolution services?

Accepted Answer

/etc/nsswitch.conf. The /etc/nsswitch.conf file controls the order of name resolution services by defining the 'hosts' database entry, which specifies the sources (e.g., files, dns) and their lookup order. If the entry is 'hosts: dns files', the system queries DNS before /etc/hosts, bypassing the local file. This file is part of the GNU C Library's Name Service Switch (NSS) framework, which governs all system databases like passwd, group, and hosts.

Answer

/etc/host.conf

Answer

/etc/resolv.conf

Answer

/etc/dnsmasq.conf

Question 6

A user submitted a print job to a CUPS printer but used the wrong options. Which command should the administrator use to cancel the job?

Accepted Answer

cancel. The `cancel` command is the correct CUPS utility to terminate a print job that has already been submitted. It accepts either a job ID (e.g., `cancel 123`) or a printer name (e.g., `cancel printer-name`) to cancel the currently active job on that printer. This command directly communicates with the CUPS daemon to remove the job from the queue.

Answer

lpstat

Answer

lprm

Answer

lpadmin

Question 7

On a Linux server using systemd and Postfix for email service, an administrator needs to diagnose a delivery failure for a local user. Which command should be used to view the most recent mail-related system journal entries?

Accepted Answer

journalctl -u postfix. `journalctl -u postfix` queries the systemd journal for all log entries associated with the `postfix` unit. Since the server uses systemd, Postfix logs are captured by journald rather than written to traditional files like `/var/log/maillog`. This command shows the most recent mail-related entries, including delivery failures, in reverse chronological order.

Answer

tail -f /var/log/maillog

Answer

systemctl status postfix

Answer

less /var/log/syslog

Question 8

An administrator wants to combine two network interfaces into a single logical interface for redundancy and increased throughput. The system uses NetworkManager. Which method is currently recommended to achieve this?

Accepted Answer

Configure a bond using nmcli. NetworkManager is the default network service on modern Linux distributions, and its recommended tool for managing network bonds is `nmcli`. Using `nmcli`, an administrator can create a bond master interface and assign slave interfaces with the `nmcli connection add type bond` and `nmcli connection add type bond-slave` commands, which ensures proper integration with NetworkManager's configuration and state management. This method is preferred over legacy tools like `ifenslave` or `teamd` because it aligns with the current systemd and NetworkManager ecosystem.

Answer

Use ifenslave to enslave interfaces

Answer

Set up a team interface using teamd

Answer

Edit /proc/net/bonding directly

Question 9

On a Debian-based system using ifupdown, which file should be edited to configure a static IP address for an interface?

Accepted Answer

/etc/network/interfaces. On Debian-based systems using the traditional ifupdown suite, the file `/etc/network/interfaces` is the central configuration file for defining network interfaces, including static IP addresses. This file is parsed by the `ifup` and `ifdown` commands to bring interfaces up or down with the specified settings, such as `address`, `netmask`, and `gateway`.

Answer

/etc/systemd/network/50-static.network

Answer

/etc/netplan/01-netcfg.yaml

Answer

/etc/sysconfig/network-scripts/ifcfg-eth0

Question 10

An administrator wants systemd-journald logs to persist across reboots. What must be created?

Accepted Answer

The directory /var/log/journal. By default, systemd-journald stores logs in a volatile tmpfs at /run/log/journal, which is cleared on reboot. To make logs persistent, the directory /var/log/journal must be created. When systemd-journald detects this directory exists, it automatically switches to persistent storage, writing logs to /var/log/journal and preserving them across reboots.

Answer

The directory /run/log/journal

Answer

The file /etc/journald.conf

Answer

The directory /var/spool/journal

Question 11

After running 'ip route show default', a system administrator sees no output. Users on that system can only communicate with hosts on the local subnet. What is the most likely cause?

Accepted Answer

The default gateway is missing. The `ip route show default` command displays the default gateway entry in the routing table. An empty output indicates that no default route is configured. Without a default gateway, the system cannot route packets to destinations outside its local subnet, which explains why users can only communicate with hosts on the local subnet.

Answer

DNS is misconfigured

Answer

A firewall is blocking all traffic

Answer

The network interface is down

Question 12

Which two commands can be used to send a test email from the command line to verify SMTP functionality? (Choose two.)

Accepted Answer

mail -s test user@example.com. The `mail` command (option C) sends an email via the local MTA, directly testing SMTP delivery. The `sendmail` command (option D) with a piped message also invokes the MTA to deliver the email, verifying SMTP functionality. Both commands rely on the system's configured MTA to handle SMTP communication.

Answer

telnet localhost 25

Answer

mutt -s test user@example.com

Answer

sendmail -bv user@example.com

Question 13

Which three files are essential for network configuration and name resolution on a typical Linux system? (Choose three.)

Accepted Answer

/etc/hosts. The `/etc/hosts` file provides static hostname-to-IP address mapping, allowing name resolution before DNS is queried. It is essential for local network configuration and fallback resolution, as defined by RFC 952 and the glibc Name Service Switch (NSS) framework.

Answer

/etc/network/interfaces

Answer

/etc/sysctl.conf

Question 14

An administrator needs to monitor real-time network bandwidth usage on a Linux server. Which two tools are specifically designed for this purpose? (Choose two.)

Accepted Answer

nload. B (nload) is correct because it is a command-line tool that displays real-time network traffic and bandwidth usage on a per-interface basis, showing incoming and outgoing data rates with a dynamic graph. E (iftop) is correct because it listens to network traffic on a specified interface and displays a real-time table of bandwidth usage per connection, similar to top for processes. Both tools are specifically designed for monitoring live bandwidth consumption, unlike general networking utilities.

Answer

netstat

Answer

traceroute

Answer

ping

Question 15

Refer to the exhibit. An administrator runs ss -tuln and gets the output above. Which of the following statements about this server is true?

Accepted Answer

The server runs SSH, HTTP, HTTPS, NTP, and mDNS.. The `ss -tuln` command displays listening TCP and UDP sockets with numeric addresses and ports. The output shows ports 22 (SSH), 80 (HTTP), 443 (HTTPS), 123 (NTP), and 5353 (mDNS). Therefore, the server is listening for SSH, HTTP, HTTPS, NTP, and mDNS services. Option D correctly lists all these services.

Answer

The server only runs SSH and DNS.

Answer

The server runs SSH and NTP only.

Answer

The server only runs SSH and HTTP.