LPIC-1 Essential System Services and Networking Practice Test 4 — 15 Questions

Question 1

An administrator is troubleshooting a DNS issue. The command 'dig @8.8.8.8 example.com' returns a response, but 'host example.com' returns 'Host not found'. Which of the following is the most likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The /etc/resolv.conf file is misconfigured.. The command 'dig @8.8.8.8 example.com' succeeds, proving that the DNS server at 8.8.8.8 is reachable and functional, and that network connectivity is fine. However, 'host example.com' fails because it uses the system's default resolver, which reads /etc/resolv.conf to determine which DNS server to query. If /etc/resolv.conf is misconfigured (e.g., missing or incorrect nameserver entries), the resolver cannot reach a valid DNS server, resulting in 'Host not found'.

Answer

The network interface is down.

Answer

The /etc/hosts file is corrupt.

Answer

The DNS server at 8.8.8.8 is not responding.

Question 2

Which THREE of the following are valid files or directories used by the Domain Name System (DNS) resolution process on a Linux system?

Accepted Answer

/etc/host.conf. Option A, /etc/host.conf, is correct because it is a legacy configuration file that tells the resolver library the order in which resolution services are queried (e.g., 'order hosts,bind'), directly affecting how hostnames are resolved. Option B, /etc/resolv.conf, is correct because it defines the DNS resolver configuration, listing nameserver IP addresses, the search domain, and options such as ndots and timeout used by the resolver. Option E, /etc/nsswitch.conf, is correct because its 'hosts:' line specifies the Name Service Switch order (e.g., 'files dns') that determines whether /etc/hosts, DNS, or other sources are consulted during name resolution. Option C, /etc/named.conf, is not part of the client resolution process; it is the main configuration file for the BIND (named) DNS server daemon. Option D, /etc/sysconfig/network, is a Red Hat-style file for general network settings like hostname and gateway, not a DNS resolver file.

Answer

/etc/named.conf

Answer

/etc/sysconfig/network

Question 3

Order the steps to mount an NFS share from a remote server.

Accepted Answer

Install NFS client, then create mount point directory, then run mount command, then verify the mount. NFS mounting requires the client package, a local directory, and the mount command with server and export path.

Answer

Create mount point directory, then install NFS client, then run mount command, then verify the mount

Answer

Install NFS client, then run mount command, then create mount point directory, then verify the mount

Answer

Run mount command, then install NFS client, then create mount point directory, then verify the mount

Question 4

Match each Linux command to its primary function.

Accepted Answer

cp: Copy files or directories. The correct matches are: cp for copying files, grep for searching text, and chmod for changing permissions. Common confusions include mixing these commands due to similar syntax or overlapping contexts.

Answer

cp: Search text using patterns

Answer

grep: Change file permissions

Answer

chmod: List directory contents

Question 5

A user reports that they cannot access the company's web server. The administrator confirms the server is running and network connectivity is fine. Which command should be used to verify that the HTTP service is listening on the correct port?

Accepted Answer

ss -tlnp. `ss -tlnp`, is correct because it lists TCP listening sockets with their port numbers and associated processes. The `-t` flag filters for TCP, `-l` shows only listening sockets, `-n` displays numeric addresses and ports (avoiding DNS lookups), and `-p` reveals the process ID/name. This directly verifies whether the HTTP service (typically port 80 or 443) is actively listening on the expected interface.

Answer

ping 127.0.0.1

Answer

netstat -rn

Answer

iperf3 -c localhost

Question 6

A DHCP server assigns IP addresses to clients, but some clients are not receiving the correct gateway. Which configuration file should be checked on the DHCP server?

Accepted Answer

/etc/dhcp/dhcpd.conf. The DHCP server configuration file on Linux systems is typically located at /etc/dhcp/dhcpd.conf (or /etc/dhcpd.conf on some older distributions). This file contains the subnet declarations, option definitions (such as option routers for the default gateway), and other parameters that the DHCP server uses to assign IP addresses and configuration details to clients. If clients are not receiving the correct gateway, the 'option routers' directive within this file should be checked and corrected.

Answer

/etc/dhcpd.conf

Answer

/etc/dhcp/dhclient.conf

Answer

/etc/resolv.conf

Question 7

A sysadmin notices that after modifying iptables rules, the SSH service is unreachable from a specific subnet (192.168.1.0/24). Which command should be used to view the current rules with line numbers for easier identification?

Accepted Answer

iptables -L --line-numbers. The `iptables -L --line-numbers` command displays all current iptables rules in the default filter table with line numbers prepended to each rule. This allows the sysadmin to easily identify and reference specific rules (e.g., for deletion or insertion) when troubleshooting why SSH traffic from 192.168.1.0/24 is being dropped or rejected.

Answer

iptables -L

Answer

iptables -t raw -L

Answer

iptables -t nat -L

Question 8

A company is deploying a new web application and needs to ensure high availability. They have two web servers and want to use DNS round-robin. Which DNS record type is most appropriate?

Accepted Answer

A. DNS round-robin distributes traffic across multiple servers by returning multiple A records for a single hostname in a rotating order. An A record maps a hostname to an IPv4 address, so using multiple A records for the same name is the standard method for DNS-based load balancing. This allows each web server to be reached via its own IP address, enabling high availability without additional hardware or software.

Answer

MX

Answer

PTR

Answer

CNAME

Question 9

A sysadmin is troubleshooting a connectivity issue between two servers in different subnets. The output of 'traceroute 192.168.2.10' shows packets reaching a router but not the destination. The router's firewall uses iptables. Which rule would prevent the traceroute from completing?

Accepted Answer

-A INPUT -p icmp --icmp-type port-unreachable -j DROP. Traceroute relies on ICMP Time Exceeded messages from intermediate routers and an ICMP Port Unreachable message from the destination to signal completion. Dropping ICMP type 3 (Destination Unreachable) packets, specifically port-unreachable (code 3), prevents the final response from reaching the source, causing traceroute to hang after reaching the last hop.

Answer

-A INPUT -i lo -j LOG

Answer

-A INPUT -p udp -j ACCEPT

Answer

-A INPUT -p tcp --dport 80 -j REJECT

Question 10

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 11

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 12

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 13

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 14

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 15

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