Understanding how a VPN works helps you use it more effectively and choose the right provider. The core mechanics involve three steps: tunneling, encryption, and IP substitution.
Step-by-Step: What Happens When You Connect
- Authentication - Your VPN client connects to a VPN server and verifies your credentials. A secure session key is established using asymmetric encryption (similar to HTTPS).
- Tunneling - Your device creates an encrypted "tunnel" to the VPN server. All network traffic is routed through this tunnel, including DNS queries.
- IP substitution - The VPN server makes requests to websites on your behalf. Sites see the server's IP address, not yours.
- Decryption and return - The server receives the website's response, encrypts it, and sends it back through the tunnel to your device.
What Your ISP Can See
| Without VPN | With VPN |
|---|---|
| Every domain you visit | Only that you connected to a VPN server |
| Content of unencrypted requests | Encrypted blob (cannot read) |
| Your DNS queries | Nothing (DNS goes through VPN) |
| Your real IP | Your real IP (when connecting to VPN, not to websites) |
VPN Kill Switch
A kill switch is a safety feature that cuts your internet connection if the VPN drops unexpectedly. This prevents your real IP from briefly being exposed during a reconnection. See: what is a VPN kill switch.
Does a VPN Protect Against DNS Leaks?
A good VPN routes all DNS queries through its own servers. If it does not, your DNS requests bypass the tunnel - a DNS leak that reveals your browsing to your ISP. Test yours with our VPN Leak Test.
People Also Ask
- How does a VPN work for dummies?
- Imagine mailing a letter inside a sealed box to a trusted friend. Your friend opens the box, reads your letter, and forwards it to the real recipient. The recipient sees your friend's address, not yours. The VPN server is that trusted friend.
- Is there a downside to having a VPN?
- Slight speed reduction (5-20%), subscription cost, and the fact that you are trusting the VPN provider with your data instead of your ISP. Choose a no-log provider with an independent audit.
Related: What is a VPN? | VPN leaks | Test your VPN