UNSUBACK Unsubscribe acknowledgment

The UNSUBACK message is sent by the broker to the client to confirm receipt of an UNSUBSCRIBE message.

Fixed header

The table below shows the fixed header format.

bit 7 6 5 4 3 2 1 0
byte 1 Message Type (11) DUP flag QoS level RETAIN
  1 0 1 1 x x x x
byte 2 Remaining length (2)
  0 0 0 0 0 0 1 0
QoS level
Not used.
DUP flag
Not used.
RETAIN flag
Not used.
Remaining Length
The length of the Variable Header (2 bytes).

Variable header

The variable header contains the Message ID for the UNSUBSCRIBE message that is being acknowledged. The table below shows the format of the variable header.

bit 7 6 5 4 3 2 1 0
byte 1 Message ID MSB
byte 2 Message ID LSB

Payload

There is no payload.