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CCNA Security Exam Cram (Exam IINS 640-553) by Eric L. Stewart

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Overview of VPN Technology

Virtual Private Networks (VPNs) are “virtual” in that they can either replace or, at least, complement existing network circuits, whether dial-in or between sites. VPNs are virtual in that sense, but hopefully there is nothing virtual about their privacy! According to Cisco, a good working definition of a VPN is as follows:

“A VPN [is] an encrypted connection between private networks over a public network, usually the Internet.”

Note

This is the definition that we use in this Exam Cram; although there are a number of other technologies that are called VPNs, they don’t provide for encryption and are thus hardly private. Historically, anything that created an IP tunnel was called a VPN. With such a loose definition, ...

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