Should only one connection be established or can there be multiple?

The number of simultaneously established connections depends on the context and the technology used.

For example, in network programming in Java, you can have multiple concurrent connections (sockets) with different servers or clients. In multi-threaded applications, it is common to open several connections for parallel processing.

In some cases, such as working with a database through a connection pool, there may be multiple active connections at the same time to improve performance.

However, in some protocols or applications, there may be a restriction to a single connection, for example, if the server only supports one connection with a client.

Thus, the answer is: there can be either one or multiple connections, depending on the requirements and architecture of the application.