SK0-004 · Question #889
A server administrator has run the netstat 璦no command locally on a system. Upon inspection, the administrator notices a listener for port 123 is set up on the server. Which of the following can the…
The correct answer is D. The network time protocol and role are configured on the server. Port 123 is the IANA-assigned UDP port for NTP (Network Time Protocol), so a listener on that port confirms the NTP role is running on the server.
Question
A server administrator has run the netstat 璦no command locally on a system. Upon inspection, the administrator notices a listener for port 123 is set up on the server. Which of the following can the administrator conclude about the server role running on the system?
Options
- AThe dynamic host configuration protocol and role are configured on the server.
- BThe remote desktop protocol and role are configured on the server.
- CThe distribution network service provider and role are configured on the server.
- DThe network time protocol and role are configured on the server.
How the community answered
(37 responses)- A3% (1)
- B5% (2)
- C3% (1)
- D89% (33)
Why each option
Port 123 is the IANA-assigned UDP port for NTP (Network Time Protocol), so a listener on that port confirms the NTP role is running on the server.
DHCP uses UDP ports 67 (server) and 68 (client), not port 123, so the listener does not indicate a DHCP role is configured.
RDP (Remote Desktop Protocol) uses TCP port 3389, not port 123, so the listener is unrelated to remote desktop services.
There is no recognized protocol or IANA-assigned standard service called 'distribution network service provider'; this is not a valid server role associated with port 123.
Port 123 is the reserved port for NTP as defined in RFC 5905, used by servers to synchronize clocks across a network. A listener on port 123 indicates the system is operating as an NTP server or running an NTP daemon. This is a standardized well-known port that uniquely identifies the NTP service role on any system.
Concept tested: Well-known port number identification for NTP
Source: https://www.rfc-editor.org/rfc/rfc5905
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