Which of the following is a mechanism that allows authentication of dial-in and other network
connections?

A.
VPN

B.
NTFS

C.
RADIUS

D.
Single Sign-On

Explanation:
RADIUS is a mechanism that allows authentication of dial-in and other network connections.
RADIUS is a client/server protocol that runs in the application layer, using UDP as transport. The
Remote Access Server, the Virtual Private Network server, the Network switch with port-based
authentication, and the Network Access Server are all gateways that control access to the network,
and all have a RADIUS client component that communicates with the RADIUS server. The RADIUS
server is usually a background process running on a UNIX or Windows NT machine.
RADIUS serves three functions:
To authenticate users or devices before granting them access to a network
To authorize those users or devices for certain network services
To account for usage of those services
certificate authority within a single sign-on system. A single sign-on server will issue digital
certificates into the client system, but never stores them. Users can execute programs, etc. with the
temporary certificate. It is common to find this solution variety with x.509-based certificates.

supports file-level security, compression, and auditing. It also supports large volumes and powerful
storage solution such as RAID. The latest feature of NTFS is its ability to encrypt files and folders to
protect sensitive data.
supplies network connectivity over a possibly long physical distance. A virtual private network is a
network that uses a public telecommunication infrastructure, such as the Internet, to provide
remote offices or individual users with secure access to their organization’s network. A virtual
private network can be contrasted with an expensive system of owned or leased lines that can only
be used by one organization. The goal of a VPN is to provide the organization with the same
capabilities, but at a much lower cost.
A VPN works by using the shared public infrastructure while maintaining privacy through security
procedures and tunneling protocols such as the Layer Two Tunneling Protocol (L2TP). In effect, the
protocols, by encrypting data at the sending end and decrypting it at the receiving end, send the
data through a tunnel that cannot be entered by data that is not properly encrypted. An additional
level of security involves encrypting not only the data, but also the originating and receiving network
addresses.