How Does a VPN Work? Understanding VPN vs No VPN

Key takeaways

• A VPN encrypts traffic between your device and the VPN server and replaces your visible IP address.
• It protects against snooping on untrusted networks such as public Wi-Fi.
• It does not stop malware, phishing, or tracking by logged-in accounts, and the provider can see your traffic.
• Choose protocols like WireGuard or OpenVPN and test for DNS leaks.

How it works, step by step

1. Your VPN app connects to a VPN server and agrees on encryption keys.
2. A virtual network interface appears on your device.
3. Your traffic is encrypted and wrapped inside packets sent to the VPN server. This is called tunnelling.
4. The VPN server decrypts the traffic and forwards it to the website.
5. Replies come back to the server, which encrypts and returns them through the tunnel.

Your Wi-Fi owner and ISP see that you are connected to a VPN server and how much data moves, but not the pages you visit or the content. The website sees the VPN server's IP address, not yours.

VPN versus no VPN

Most websites already use HTTPS, which encrypts the content between you and the site. A VPN adds a layer, hiding destinations from the local network and ISP, and is most useful on untrusted Wi-Fi or when connecting to a company network.

Protocols

• WireGuard: a modern, small and fast protocol.
• OpenVPN: long established, flexible, widely supported.
• IPsec with IKEv2: common in corporate and mobile settings.

Avoid obsolete protocols. Details are in the relevant standards, such as those listed by the IETF.

Types of VPN

• Remote-access VPN: an employee connects to the company network.
• Site-to-site VPN: two offices connect their networks.
• Consumer VPN service: a commercial provider routes your internet traffic through its servers.

What a VPN does not do

• It does not protect you from malware or phishing.
• It does not hide who you are from sites where you log in.
• It does not stop browser fingerprinting and tracking cookies.
• It moves trust: your provider can see your traffic metadata and, if it chooses, more. A "no logs" claim is a promise, not proof.
• A free VPN may make money from your data.

Check for leaks

A poorly configured VPN can leak your real IP address or your DNS queries. After connecting, check which DNS servers are in use. Commands such as resolvectl status on Linux or ipconfig /all on Windows show them.

Choosing a VPN

• Use a company VPN for work. Do not replace it with a consumer service.
• Prefer a provider with a clear privacy policy and independent audits where available.
• Look for modern protocols and a kill switch, which blocks traffic if the tunnel drops.
• Be wary of "free" and "unlimited" claims.

India notes

Using a VPN is common for business and privacy. Indian regulators, including CERT-In, have issued directions affecting VPN and cloud service providers, such as record-keeping requirements. These rules change, so check current guidance and your organisation's policy. Using a VPN to commit a crime remains illegal.

Related reading

For more detail, see how VPN tunnelling works, what the purpose of a VPN tunnel is and top VPNs for privacy.

Next steps

To learn how VPNs and network security are built, see the Cisco CCNA course or the Network Defender (CND) course.