2.2.6 BecomeBackup Browser Frame
When a local master browser server for a machine group wants to promote a potential browser server to backup browser server, it MUST send a BecomeBackup frame by using the NetBIOS group name <machine group>[0x1E] and mailslot \MAILSLOT\BROWSE.
The definition of the BecomeBackup frame MUST be as follows.
0x0B (1 byte): The 8-bit opcode that identifies this structure as a BecomeBackup frame. This opcode MUST have a value of 0x0B.
BrowserToPromote (variable): MUST be a null-terminated ASCII string that is less than or equal to 16 bytes in length, including the null terminator, which MUST be the name of the browser server to be promoted to backup.