List two advantages and two disadvantages of VPNs.

What will be an ideal response?

Advantages:
Far less expensive than leased lines
Many elements working together provide strong security
Standards and protocols used in VPNs are well developed and widely used
Can result in less overall complexity in an organization's network
Can make use of a company's existing broadband connection

Disadvantages:
Can be complex to configure
Can result in slower data transfer rates than a leased line
Depends on the often unpredictable Internet; if your ISP or other parts of the Internet go down, your VPN goes down
Requires administrators to install VPN client software on remote computers
VPN hardware and software from different vendors might prove incompatible because they use different protocols