In fact, hard is the default so you do not need to specify it explicitly. The NFS HOWTO recommends the options hard and intr unless there is a good reason to do otherwise. The option intr ensures that if the server is no longer responding, the program that is accessing the mount can be interrupted by a kill signal.
You can also control whether the NFS connection takes place over TCP or UDP. Traditionally, UDP was the default. In recent versions, this has been reversed and by default the connection takes place over TCP.
In the case of UDP, the connection is stateless, which means that the server can be restarted without breaking the connection. However, UDP is less efficient if any packets are being dropped on the network. If you use TCP, every packet is acknowledged and resent if it does not arrive. In the case of UDP, only the completion of the entire request is acknowledged.
To force the connection to take place over UDP, use a mount command such as this:
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