Run MSTP on the network. When you view the configuration on the root switch of an MSTP domain, the following command is obtained. As shown in the figure, please estimate the network size of the MSTP domain where the root switch resides.
[SWA]display stp
——- [CIST Global Info] [Mode MSTP] ——
CIST Bridge: 0.000f-e212-f8e1
Bridge Times: Hello 2s MaxAge 20s FWDly 15s MaxHop 30
CIST Root/ERPC: 0.000f-e212-f8e1/0
CIST RegRoot/IRPC: 0.000f-e212-f8e1/0
CIST RootPortId: 0.0
BPDU-Protection: disabled
CIST Root Type: PRIMARY root
TC or TCN received :3
Time since last TC: 0 days 1h:23m:36s
A . Less than 10 units
B . Less than 20 units
C . Less than 30 units
D . Less than 40 units
Answer: C