LFCS Certification Network Service Configuration 2

Question 1

Which command displays the current listening TCP and UDP ports along with the process using each port?

Accepted Answer

netstat -tulpn

Answer

netstat -tulpn shows TCP/UDP listening ports (-l), process names (-p), and numeric addresses (-n).

Question 2

Which file must you edit to make a custom DNS name resolve locally before querying external DNS servers?

Accepted Answer

/etc/hosts

Answer

/etc/hosts is checked first (by default nsswitch.conf order) and maps hostnames to IPs locally.

Question 3

What is the purpose of the /etc/resolv.conf file?

Accepted Answer

Lists DNS nameserver addresses and search domains

Answer

/etc/resolv.conf specifies nameserver IPs and optional search/domain directives used by the resolver library.

Question 4

Which systemd unit type is used to expose a service on a network socket, enabling socket activation?

Accepted Answer

.socket

Answer

systemd .socket units manage socket activation, starting the corresponding service only when a connection arrives.

Question 5

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?

Accepted Answer

bash -c 'echo > /dev/tcp/host/443'

Answer

Bash's built-in /dev/tcp pseudo-device can open a TCP connection without any external tool.

LFCS Certification Practice Test