3.1.6 Timer Events
When a GetBackupListRequest timer expires without receiving a GetBackupListResponse, the GetBackupListRequest frame MAY be retransmitted. The delay MUST be at least twice the expected service time, which MUST be 1 second.<30> Before resending, the client MAY modify TokenValue.<31> If TokenValue is modified, the client MUST set the Token field of the GetBackupListRequest to the new value of TokenValue, and resend the GetBackupListRequest.
If the local master browser for a machine group fails to respond to the GetBackupListRequest after an implementation-defined number of retries, the client MUST set the Uptime value with the time difference, in seconds, between the current time and BrowserClientUpTime, and the client MUST force an election by Sending a RequestElection Frame, as specified in section 18.104.22.168. If the client is unable to retrieve a list of browser servers from the local master browser server, it MAY attempt to retrieve a list of backup browser servers by sending a GetBackupListRequest frame directly to the domain master browser for that domain by using the unique name <domain>[0x1B] that is registered by the domain master browser. The value of the retry count MUST be 3.