An enterprise router is configured with the command `ntp master 4` and has an active server association configured via `ntp server 10.20.30.5` (which is a Stratum 2 reference source). The command `show ntp status` indicates that the clock is currently synchronized to 10.20.30.5. Which TWO statements accurately describe the NTP operational behavior and stratum hierarchy in this deployment? (Select two.)
- The router functions at Stratum 3 because it dynamically calculates its stratum level by incrementing the Stratum 2 source's level by 1 while synchronized.Answer
- If connectivity to 10.20.30.5 is lost and all external NTP references become unreachable, the router will fall back to serving time at Stratum 4.Answer
- CThe router adds its configured `ntp master 4` value to the upstream server's Stratum 2 value, advertising Stratum 6 to downstream clients.
- DConfiguring `ntp master 4` overrides external NTP server associations, forcing the router to ignore 10.20.30.5 and synchronize exclusively to its local clock.
Answer
The router functions at Stratum 3 by incrementing the external Stratum 2 source by 1, and if the external source becomes unreachable, the router falls back to operating at Stratum 4 using its internal clock.
When a router is actively synchronized to an external Stratum 2 NTP server, its operational stratum level becomes Stratum 3 (upstream stratum + 1). The configured `ntp master 4` command acts as a fallback mechanism; if external synchronization is lost, the router maintains NTP server capability by serving time to downstream clients at Stratum 4.
Step-by-Step Solution
Key Concept
NTP Stratum Calculation and Master Fallback Operation