CompTIA A+ Core 1 (220-1201)NetworkingHard
A network engineer notices that several servers in a data center have slightly inconsistent system clocks, causing authentication failures with time-sensitive security certificates. Which port should be verified as open to allow the servers to synchronize their clocks with a time server?
- AUDP 161
- BUDP 123
- CTCP 137
- DTCP 143
Show answer & explanationAnswer & explanation
Correct answer: B. UDP 123
Network Time Protocol (NTP) uses UDP port 123 to synchronize system clocks across devices. Accurate time synchronization is critical for certificate validation and Kerberos authentication, which are sensitive to clock drift.
Why the other options are wrong
- A. UDP 161 is used by SNMP for network device monitoring.
- C. TCP 137 is associated with NetBIOS name service, not time sync.
- D. TCP 143 is used by IMAP for email retrieval.
NTP Port 123
Network Time Protocol uses UDP port 123 to synchronize clocks between computers and network devices.
- Critical for certificate validation and Kerberos authentication
- Uses UDP for lightweight, connectionless communication
- Clock drift can cause security and logging inconsistencies
Memory trick: NTP: one-two-three, keep the clocks in harmony.