In enterprise networking, what are the typical three main categories of Virtual Private Networks (VPNs) used to secure connectivity?

Introduction / Context:
Virtual Private Networks, or VPNs, are used to create secure tunnels over untrusted networks like the internet. They allow private data to be encrypted and transported between remote sites, business partners, and mobile workers. Many networking courses and Cisco certifications describe VPNs through three main categories based on who connects to whom. This question asks you to identify those three typical categories.

Given Data / Assumptions:

We are looking for broad categories of VPN deployments, not low level protocol types.
VPNs can connect individuals, internal sites, or external partner sites.
We assume an enterprise or service provider context.

Concept / Approach:
The three commonly cited categories of VPNs are remote access VPNs, site to site intranet VPNs, and site to site extranet VPNs. Remote access VPNs connect individual users, such as employees working from home or on the road, to a central corporate network. Site to site intranet VPNs connect multiple sites of the same organization, such as branch offices, over a secure tunnel. Site to site extranet VPNs connect the networks of business partners, suppliers, or customers, providing controlled secure access between organizations. These categories describe who owns the endpoints and how the VPN is used, rather than the underlying technical details only.

Step-by-Step Solution:
Step 1: Recall the high level VPN categories often mentioned in enterprise networking literature.Step 2: Identify remote access VPNs for individual users connecting into the corporate network.Step 3: Distinguish between intranet site to site VPNs (within one organization) and extranet site to site VPNs (between different organizations).Step 4: Select the option listing remote access, site to site intranet, and site to site extranet VPNs.

Verification / Alternative check:
You can verify by imagining typical use cases. A salesperson dialing in securely from a hotel uses a remote access VPN. A branch office connected securely to headquarters uses a site to site intranet VPN. A supplier network that securely exchanges data with a customer network uses a site to site extranet VPN. These scenarios match the categories given in the correct option and are commonly described in Cisco and networking textbooks.

Why Other Options Are Wrong:
Option B is wrong because labeling VPNs as wireless, wired, or mobile only categorizes them by underlying medium, not by typical deployment use cases.
Option C is wrong because terms like local, regional, and global describe geographic scope, not functional VPN types used to secure different relationships.
Option D is wrong because data, voice, and video are different traffic types, not standard categories of VPN deployments.

Common Pitfalls:
Some learners confuse VPN categories with VPN tunneling protocols such as IPsec or SSL, which is a different classification dimension. Others may think only of remote access VPNs and forget that site to site VPNs are widely used. When preparing for exams, keep both the use case based categories and the protocol based categories in mind and note that this question specifically asks about the typical three categories in terms of deployment and connectivity patterns.

Final Answer:
Remote access VPNs, site to site intranet VPNs, and site to site extranet VPNs