Which of the following statements about clock sources is incorrect?

A. Internal clock sources have the lowest priority because of their low precision.

B. Generally, tributary clocks are not used as the clock sources of devices.

C. The same SSM protocol is selected for all NEs in a clock protection subnet.

D. If the standard SSM protocol is enabled, you need to set the clock source ID.

When the transmit end detects that the b6-b8 of the K2 byte is 110, it indicates that the () alarm is reported at the transmit end.

A. MS-AIS

B. R-LOS

C. R-LOF

D. MS-RDI

The PRBS can be used to test whether an SDH service is normal and whether the protection switching function is normal.

A. TRUE

B. FALSE

A MAC address consists of 48 bits and is globally unique. Which of the following is the meaning of the MAC address whose eighth bit is 1?

A. Unicast address

B. Bicast address

C. Multicast address

D. Broadcast address

Which of the following bytes can be used for the orderwire phone between two REG devices?

A. E1

B. E2

C. E1 and E2

D. None of the above

The fiber core refractive index n1 must be ( ) the cladding layer refractive index n2, which is a necessary condition for transmitting optical signals in optical fibers.

A. higher than

B. lower than

C. equal to

Linear MSP (LMSP) has two modes; 1+1 and 1:1. Extra services can be configured for the protection channel only in the 1:1 mode of LMSP.

A. TRUE

B. FALSE

Which of the following statements about overhead bytes is incorrect?

A. A1 and A2 are framing bytes. These bytes are used to separate STM-1 frames in a signal flow.

B. J0 is a regenerator section trace byte. This byte is used to repeatedly transmit a section access point identifier, so that the receive end can verify its continuous connection to the specified transmit end.

C. B1 is bit interleaved parity-8 (BIP-8). This byte is used to monitor bit errors at the regenerator section layer.

D. E1 and E2 are orderwire bytes. These bytes are used to provide a voice channel for orderwire connections.

The TAG attribute cannot be set for the internal port VCTRUNK of the board on the NMS.

A. TRUE

B. FALSE

Which of the following is the maximum number of OSN 3500 subracks that can be installed in a 2.2 m cabinet?

A. 1

B. 2

C. 3

D. 4