Challenge Handshake Authentication Protocol (CHAP) is an encrypted authentication mechanism that prevents transmission of the actual password on the connection. The NAS sends a challenge, which consists of a session ID and an arbitrary challenge string, to the remote client. The remote client must use the MD5 one-way hashing algorithm to return the user name and a hash of the challenge, session ID, and the client’s password. The user name is sent as plain text.
The biggest advantage of RIP is that it is extremely simple to configure and deploy. The biggest disadvantage of RIP is its inability to scale to large or very large networks. The maximum hop count used by RIP routers is 15. Networks that are 16 hops or more away are considered unreachable. As networks grow larger in size, the periodic announcements by each RIP router can cause excessive traffic. Another disadvantage of RIP is its high recovery time. When the network topology changes, it might take several minutes before the RIP routers reconfigure themselves to the new network topology. While the network reconfigures itself, routing loops might form that result in lost or undeliverable data.
In short, it's time to start thinking about protecting your personal information. That's where virtual private networks, or VPNs, come in. These services use simple software to protect your internet connection, and they give you greater control over how you appear online, too. While you might never have heard of VPN services, they are valuable tools that you should understand and use. So who needs a VPN? The short answer is that everyone does. Even Mac users can benefit from a VPN.