The server program is ................. because it is always, available waiting for a client request.
The server program is ................. because it is always, available waiting for a client request.
The correct option is B Passive
The server program is
Passive because it is always, available waiting for a client request.
The analogy given below
is often very useful in understanding many such networking concepts. The
analogy is of a number of people in a room communicating with each other by way
of talking. In a typical scenario, if A has to talk to B, then he would call
out the name of B and only if B was listening would he respond. In case B
responds, then one can say that a connection has been established. Henceforth
until both of them desire to communicate, they can carry out their
conversation.
There is a general misconception that servers
necessarily provide some service and is therefore called a server. For example
an e-mail client provides as much service as an mail server does. Actually the term
service is not very well defined. So it would be better not to refer to the
term at all. In fact servers can be programmed to do practically anything that
a normal application can do. In brief, a server is just an entity that
listens/waits for requests.
To send a request, the
client needs to know the address of the server as well as the port number which
has to be supplied to establish a connection. One option is to make the server
choose a random number as a port number, which will be somehow conveyed to the
client. Subsequently the client will use this port number to send requests.
This method has severe limitations as such information has to be communicated
offline, the network connection not yet being established. A better option
would be to ensure that the server runs on the same port number always and the
client already has knowledge as to which port provides which service. Such a
standardization already exists. The port numbers 0-1023 are reserved for the
use of the superuser only. The list of the services and the ports can be found
in the file /etc/services.
The server program is Passive because it is always, available waiting for a client request.
The analogy given below is often very useful in understanding many such networking concepts. The analogy is of a number of people in a room communicating with each other by way of talking. In a typical scenario, if A has to talk to B, then he would call out the name of B and only if B was listening would he respond. In case B responds, then one can say that a connection has been established. Henceforth until both of them desire to communicate, they can carry out their conversation.
There is a general misconception that servers necessarily provide some service and is therefore called a server. For example an e-mail client provides as much service as an mail server does. Actually the term service is not very well defined. So it would be better not to refer to the term at all. In fact servers can be programmed to do practically anything that a normal application can do. In brief, a server is just an entity that listens/waits for requests.
To send a request, the client needs to know the address of the server as well as the port number which has to be supplied to establish a connection. One option is to make the server choose a random number as a port number, which will be somehow conveyed to the client. Subsequently the client will use this port number to send requests. This method has severe limitations as such information has to be communicated offline, the network connection not yet being established. A better option would be to ensure that the server runs on the same port number always and the client already has knowledge as to which port provides which service. Such a standardization already exists. The port numbers 0-1023 are reserved for the use of the superuser only. The list of the services and the ports can be found in the file /etc/services.
