Clients that only read information offered need not necessarily have a permanent IP address. However, when logged into the internet, a client requires a unique IP address. This IP Address enables the internet server called, to reply accurately.
The ISP’s server via which client connects to the internet, temporarily assigns a unique IP address to the client. In India VSNL (Vidhesh Samachar Nigam Ltd) was the only ISP in the beginning. Whenever a client logs into the Internet via a VSNL ISP, the VSNL server temporarily (which called dynamically) assigns a unique IP address to the computer that successfully logs in to the Internet.
ISP’s purchase a block of unique IP addresses from Networking companies who is authorized to assign them. So, each time the same client logs into the ISP’s Server, the client will be assigned a unique but may be different IP address temporarily. This is the technique of ‘Dynamically assigning’ a IP address to a client when required.
The client computer logs into the ISP’s Server using a dial-up line and a modem. After a successful login ISP’s server passes one IP address from the block of IP addresses purchased, to the computer logged in. TCP/IP stack of client computers configured to get an IP address dynamically from the ISP’s DHNS Server. Once a computer is logged on to the internet and has a unique IP address, any other computer in the internet that is aware of this IP address can communicate with it.