Network Service Configuration Flashcards
7 cards from real LFCS Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Network Service Configuration flashcards as text
Which command displays the current listening TCP and UDP ports along with the process using each port?
Answer: netstat -tulpn
netstat -tulpn shows TCP/UDP listening ports (-l), process names (-p), and numeric addresses (-n).
Which file must you edit to make a custom DNS name resolve locally before querying external DNS servers?
Answer: /etc/hosts
/etc/hosts is checked first (by default nsswitch.conf order) and maps hostnames to IPs locally.
What is the purpose of the /etc/resolv.conf file?
Answer: Lists DNS nameserver addresses and search domains
/etc/resolv.conf specifies nameserver IPs and optional search/domain directives used by the resolver library.
Which systemd unit type is used to expose a service on a network socket, enabling socket activation?
Answer: .socket
systemd .socket units manage socket activation, starting the corresponding service only when a connection arrives.
You want to test whether TCP port 443 is open on a remote host without installing extra tools. Which command works on most Linux systems?
Answer: bash -c 'echo > /dev/tcp/host/443'
Bash's built-in /dev/tcp pseudo-device can open a TCP connection without any external tool.
Which directive in an SSH server configuration (/etc/ssh/sshd_config) disables password-based logins?
Answer: PasswordAuthentication no
Setting PasswordAuthentication no forces key-based authentication and prevents password logins.
Which command reloads the systemd daemon after editing a unit file, without restarting services?
Answer: systemctl daemon-reload
systemctl daemon-reload re-reads unit files from disk; services keep running until explicitly restarted.
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Sources & references
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- docs.linuxfoundation.org — Renewal, score release, exam format, passing score · verified Oct 2026
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