Which directive of the smb.conf file ensures a Samba server will win broadcast elections for the master browser?

The directive that ensures a Samba server will win broadcast elections for the master browser is set with the value of os level to 255.

In Samba's configuration, the "os level" parameter determines the priority of the Samba server in the network's master browser election process. A higher os level value indicates a greater likelihood that the Samba server will be elected as the master browser. The master browser is responsible for maintaining a list of all the servers and shared resources in the network, thus its election is critical for efficient networking in mixed environments.

Setting os level to 255 gives the Samba server the highest possible priority, essentially guaranteeing that it will be elected as the master browser in any broadcast election scenario. Values lower than this, such as 31 or 15, would still allow the server to participate in the election but would not ensure it will win against others potentially configured with higher values. A value of 0 indicates that the Samba server does not participate in the browser election at all, making it ineffective in this context.

Therefore, setting os level to 255 is the correct answer for ensuring that a Samba server becomes the master browser through a broadcast election process.