Essential System Services and Networking

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?

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

An Ubuntu 20.04 server needs a static IP address. The administrator has created a netplan YAML file at /etc/netplan/01-netcfg.yaml. What is the next step to apply the configuration?

A company manages a cluster of 50 web servers running Ubuntu 20.04. The servers are configured to synchronize time with an internal NTP server at 10.0.0.100 using the default ntpd. The NTP server itself syncs with external stratum 2 servers. Recently, the security team implemented a restrictive iptables firewall on all servers, allowing only essential services. Several servers in the 10.0.1.0/24 network now report time drift and ntpq -p shows all peers with '?' status. A network engineer runs tcpdump on one affected server and sees no NTP replies from 10.0.0.100. The NTP server's firewall is configured to allow inbound NTP from 10.0.0.0/24 only. The engineer also notes that the server's /etc/ntp.conf contains the line 'restrict 10.0.0.100' (which is incorrect) and that ntpq -crv shows 'sync target not reachable'. Which single action will most directly resolve the synchronization issue for the affected servers?

On a modern Linux system using systemd-networkd for interface management and systemd-resolved for DNS, which THREE files are typically involved in network configuration and DNS resolution?

A developer asks the system administrator to configure a local web server for testing using Apache. The server should serve files from /var/www/test. Which directive must be set in the Apache configuration to set this document root?

A Linux administrator needs to check the current status of the systemd service named sshd, including whether it is active and its recent log entries. Which command should she run?

A company runs a web server using Apache with multiple virtual hosts. The administrator needs to restrict access to a specific virtual host based on the client IP address. Which configuration directive should be placed inside the <VirtualHost> block to deny IP 192.168.1.100?

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

A server uses systemd-resolved for DNS. Users report that name resolution works for external domains but fails for internal company hostnames. The administrator checks /etc/resolv.conf and sees 'nameserver 127.0.0.53'. Which action will resolve the issue?

A Linux server uses systemd-resolved for DNS resolution. Users report that hostname resolution fails intermittently. The administrator inspects /etc/resolv.conf and finds it is a symlink to /run/systemd/resolve/stub-resolv.conf with nameserver 127.0.0.53. Which command should the administrator use to verify the current DNS servers and resolution status?

After a reboot, a server fails to obtain an IP address on its sole ethernet interface. The administrator checks /etc/netplan/01-netcfg.yaml and finds the configuration looks correct. However, the interface shows no IP. The system uses systemd-networkd. Which command should be run next to apply the configuration and bring up the interface?

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.)

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

A system administrator notices that the system time is incorrect by several minutes. Which command should be used first to check the status of NTP synchronization?

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

Which TWO commands can be used to display the current firewall rules in a system using nftables? (Choose two.)

A Linux administrator is troubleshooting a server that cannot resolve external hostnames. The server has a static IP address and can ping 8.8.8.8 successfully. The administrator checks /etc/resolv.conf and finds only 'nameserver 127.0.0.53'. Which command will best help determine the actual DNS servers being used and the resolution path?

A Linux administrator needs to configure a system to use a proxy server for HTTP and HTTPS traffic for all users. Which TWO environment variables should be set in a system-wide profile script to ensure that command-line tools like curl and wget use the proxy? (Choose two.)

Which TWO tools can be used to query DNS records? (Choose two.)

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

A Linux server acts as a router between an internal network and the internet. After enabling IPv4 forwarding, clients still cannot reach external hosts. The administrator confirms the routing table is correct and the external interface is up. Which command displays the current kernel packet-filter rules so the administrator can verify whether forwarding is being blocked?

A Linux server uses nftables as its firewall. The administrator needs to allow incoming SSH (TCP/22) and HTTP (TCP/80) while dropping all other incoming traffic. Which TWO statements about implementing this are correct? (Choose two.)

Refer to the exhibit. A system administrator runs 'ip route show default' and gets this output. What does it indicate?

A Linux server uses chrony for time synchronization. The administrator notices that the system clock is drifting by several seconds per day. Which command should she use to verify which NTP servers are currently selected and the estimated offset?

Which THREE steps are required to configure a network interface with a static IP address using the ip command (assuming interface eth0)? (Choose three.)

A server runs systemd-resolved and uses a VPN. DNS queries fail intermittently. The administrator checks /etc/resolv.conf and finds it is a symlink to /run/systemd/resolve/stub-resolv.conf. Which command should be used to view the effective DNS servers and debug the issue?

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?

A technician is troubleshooting network connectivity. The server's IP is 192.168.1.10/24, and the gateway is 192.168.1.1. The server can ping the gateway but cannot ping 8.8.8.8. Which command is most appropriate to check if the default route is configured?

A system administrator notices that the NTP service on a Linux server is not synchronizing time with external NTP servers. The administrator runs 'ntpq -p' and sees that all servers listed have a 'reach' value of 0. Which of the following is the most likely cause?

A junior administrator is asked to verify which TCP ports are listening on a Linux server and which processes own them. Which command provides this information directly?

Match each Linux command to its primary function.

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?

Refer to the exhibit. A system administrator finds this line in /etc/rsyslog.conf. What is the effect of this configuration?

Which of the following commands will display the default gateway of a Linux system?

An organization's DNS server (BIND) is authoritatively serving the example.com zone. The administrator needs to add a mail exchange record for mail.example.com with priority 10. Which resource record should be added to the zone file?

Which TWO commands are commonly used to start, stop, or restart system services on a Linux system that uses systemd as its init system?

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?

A junior administrator on a systemd host needs the OpenSSH daemon to start automatically after every reboot and to begin running immediately without rebooting the machine. Which single command accomplishes both requirements?

A Linux administrator needs to configure a system to act as a router between two subnets. The system has two network interfaces: eth0 (192.168.1.1/24) and eth1 (10.0.0.1/24). Which TWO steps are required to enable routing between these subnets? (Choose two.)

A small office has a network printer with IP 192.168.1.100. The printer is shared via CUPS. A user reports that they cannot print a document from their workstation. The printer appears in the list of available printers, but when they try to print, the job hangs in the queue with status 'processing'. The administrator suspects the printer may be offline or the CUPS service is not running. Which command should the administrator run first to gather diagnostic information about the printer and its queue?

A server in a corporate network uses systemd-resolved for DNS. Internal hostnames (e.g., server.example.lan) fail to resolve, but external names (e.g., google.com) work. The /etc/resolv.conf is a symlink to /run/systemd/resolve/stub-resolv.conf. The administrator checks the systemd-resolved configuration and finds that the internal DNS server is listed globally, but the network interface has no specific DNS set. Which command should be used to assign the internal DNS server to the interface and fix resolution?

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

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?

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?

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

A user reports that they cannot connect to a remote server using SSH. The administrator checks the SSH server status and it is running. Which of the following is the most likely cause?

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?

A system administrator wants to monitor network traffic on a specific port (TCP/443) entering the server. Which command will capture packets on interface eth0 and display them in real-time?

An administrator is configuring a DHCP server to assign IP addresses to clients in the 192.168.10.0/24 subnet. The server should provide the default gateway as 192.168.10.1 and DNS server as 8.8.8.8. Which option in /etc/dhcp/dhcpd.conf defines the default gateway?

A Linux administrator needs to view the current kernel ring buffer messages to diagnose a hardware issue that occurred during boot. Which command will display these messages?

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

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?

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?

An administrator must grant a contractor temporary, passwordless sudo access to run only /usr/bin/systemctl restart nginx on a production web server. Which entry in a file under /etc/sudoers.d/ best meets this requirement while limiting privilege escalation?

A database server on a Linux system is configured to listen on TCP port 3306. The administrator wants to restrict access to the database server to only the local network (192.168.1.0/24) using iptables. Which of the following iptables rules achieves this?