Web Development 1

Dr Derek Bridge

School of Computer Science & Information Technology

University College Cork

Class exercise


The scheme

The scheme, continued

The host: IP address

The host: hostname

The Domain Name System (DNS)


A sequence of DNS servers will be consulted before a whole hostname can be converted into an IP address.

The port number

Listening on ports

Suppose a machine is running Web server software and email server software. Then requests from clients must indicate which server software should handle the request and deliver the response. This is done by including a number, called a port, with the request: 80 for the Web, and 143 for email.

Well-known port numbers

The pathname




Class exercise: What is the main problem with caching? How do you think it is solved?