Exercise 4

Exercise: Virtual Private Networks.

1] IP refers to Internet Protocol which is used to provide routing function across multiple networks, regardless of the application that are exchanging data, and also provides reliable delivery of data.
IP works at Transport layer, which provides a connectionless packet delivery service.

DNS stand for Domain Name Server, which is a internet directory service.DNS works as a “phonebook” for the internet by translating human readable computer hostnames, e.g .http://www.example.com/ ,into IP addresses, e.g. 208.77.188.166, which networking equipment needs to deliver information.
Domain Names consist of up to 63 characters
Case-insensitive, but most implementations propagate case
Alphanumeric characters and the '-' (hyphen) character are allowed
Shorter names are helpful for poor typists
Sibling nodes MUST be unique
This rule makes the entire Name Space collision-free
Leaf nodes' labels are still Domain Names
Although most people usually just call them hostnames
(Aitchison)

2] TCP Stand for Transmission Control Protocol.TCP works with IP to provide a reliable delivery.TCP support IP to support flow control and congestion mechanism. Since IP is is connection less protocol it depends on TCP to provide a confirmation message of the successful delivery of the data packet .in case the data packets are lost or damaged a negative confirmation ,in such a case the data packets are resend .
TCP also ensure that the sender does not overflow the receiver end by implementing flow control protocols. So to conclude it is appropriate to say that TCP/IP together offer a reliable delivery.

3] The following are some of the E-Business Applications:
v http://venturebeat.com/
v http://allthingsd.com/
v http://www.zdnet.com/

The following link is to the websites which provides a list of top 20 E-Business Websites ranked by a combination of Inbound Links, Google Page Rank, Alexa Rank, and U.S. traffic data from Compete and Quant cast. http://www.ebizmba.com/articles/tech-business
4] VPN refers to Virtual Private networks. The concept of VPN is to provide secure data transfer over a public network. The major benefit is that Establishing WAN options across private lines, ATMs, frame relays with IP VPNs, private networks are secure, they are also far more complex, cumbersome to set up and manage, costly to maintain, inflexible and non-scalable; and also private networks, by design, are limited. Whereas VPNs give freedom and flexibility to scale a business quickly, and cost-effectively, with rapid growth and ubiquitous nature of Internet as it’s key.



http://www.networksedge.com/jpgs/vpn.jpg
TO accomplish this the concept Tunnelling is used.Tunneling is the process of putting one packet inside another .A "tunnel" of privacy between two end-points connected by a public (non-secure) channel. This is often the Internet, but it could equally be the cellular telephone network. In a hide-in-plain-sight fashion, tunnelling provides privacy by encrypting everything that goes into and comes out of a secure tunnel. The two standards of tunnelling emerging are : Microsoft's, known as PPTP (and its derivative L2TP), and everyone else's. The latter goes by the name of the IP Security protocol, or IPSec. To know about these standards in detail the link below will help
http://www.intranetjournal.com/foundation/tunneling.shtml