Essential System Services and Networking →mediumMultiple ChoiceObjective-mapped

LPIC-1 Essential System Services and Networking Practice Question

Exhibit

Netid  State   Recv-Q  Send-Q  Local Address:Port   Peer Address:Port
tcp    LISTEN  0       128     0.0.0.0:22            0.0.0.0:*
tcp    LISTEN  0       128     0.0.0.0:80            0.0.0.0:*
tcp    LISTEN  0       128     0.0.0.0:443           0.0.0.0:*
udp    UNCONN  0       0       0.0.0.0:5353          0.0.0.0:*
udp    UNCONN  0       0       0.0.0.0:123           0.0.0.0:*

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

⚠ Common exam trap

The trap here is that candidates may overlook the UDP listening sockets (especially port 5353 for mDNS) or misidentify port 123 (NTP) as something else, leading them to select an incomplete list of services.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

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 analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The server only runs SSH and DNS.
Why it's wrong here
Port 53 is not listening; here we see NTP and mDNS.
✗
The server runs SSH and NTP only.
Why it's wrong here
HTTP, HTTPS, and mDNS are also present.
✗
The server only runs SSH and HTTP.
Why it's wrong here
It also runs HTTPS, mDNS, and NTP.
✓
The server runs SSH, HTTP, HTTPS, NTP, and mDNS.
Why this is correct
Ports 22, 80, 443, 123, and 5353 correspond to these services.

Go deeper

LPIC-1 Essential System Services and Networking Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

Related to this question