How a VPN connection works (so you can judge features)

A VPN (Virtual Private Network) typically creates an encrypted tunnel between your device and a VPN server operated by the provider. After the tunnel is established, your device sends network requests through that tunnel; the VPN server then forwards the traffic to the destination on the public internet. This design changes what the destination can observe (it generally sees the VPN server’s network location rather than your device’s direct location), while your local network observer can see that you’re using a VPN but should not be able to read the contents.

In practice, “VPN features” usually determine four things:

  • How your device chooses and maintains the tunnel (protocols, reconnection behavior, multihop options if offered).
  • What traffic the provider routes through the tunnel (full-tunnel vs split-tunneling behavior, when it applies, and any exceptions).
  • How the tunnel is protected (encryption strength, key exchange method, and safeguards against traffic escaping the tunnel).
  • How consistently it works in real networks (performance, network type support, and app stability).

Because providers implement these differently, two VPN services can both “encrypt traffic” yet differ in usability, transparency, and the likelihood of mistakes such as traffic not being protected in certain edge cases.

Core features that matter most

1) VPN protocols and connection behavior

Protocols are the agreed rules for how encryption and tunneling are performed. Common examples include OpenVPN-style implementations, WireGuard-style approaches, and IKEv2/IPsec-style approaches. The protocol you can select—and what the provider does by default—matters for reliability, compatibility across devices, and how well the connection survives network changes (e.g., switching Wi‑Fi networks).

Important related features to look for:

  • A clear default protocol and an option to choose alternatives.
  • Automatic reconnection when your network drops briefly.
  • Stability under captive portals or restrictive networks (workplaces, some hotels), where VPN connectivity can fail.

2) Kill switch and traffic leak protection

A kill switch helps ensure that if the VPN tunnel drops, your device does not continue sending traffic unprotected on the regular network interface. Some providers also provide settings for blocking local network access when the VPN is down.

Instead of treating this as a checkbox, evaluate what you can verify:

  • Whether the kill switch can be enabled on your device.
  • Whether it is designed to cover all traffic types you care about (web browsing, DNS, streaming apps, etc.).
  • Whether it behaves correctly when you manually disconnect or when the tunnel fails.

3) DNS and IPv6 handling

Even when traffic to websites is routed through the VPN tunnel, name resolution can be a separate path. VPN services often address this by using provider DNS resolvers or by routing DNS queries through the tunnel. If not handled correctly, you may experience DNS leaks (your DNS requests can reveal domains you visited) or IPv6 leaks (some traffic may bypass IPv4-only tunneling).

A good sign is when provider documentation explicitly addresses DNS behavior and IPv6 handling, and when settings exist that let you control or confirm it. Since exact implementations vary, treat “we protect your DNS” claims as something you should validate with practical tests.

4) Application support and routing options

A VPN provider can support multiple platforms (desktop and mobile) and may offer features like split tunneling (route only some traffic through the VPN). These choices affect both privacy and functionality.

Key points:

  • Does the provider support your devices and operating systems?
  • Is split tunneling present, and is it documented clearly?
  • Does the provider offer full-tunnel behavior by default?

5) Transparency signals: policies and security posture

For many users, the most important “feature” is the provider’s transparency about how they operate—within reasonable limits. Look for clear statements about:

  • What data is collected and why (and what is not).
  • How logging is handled (e.g., whether the provider claims to minimize retention).
  • Whether they publish security practices such as audits or documentation.

Given that you can’t assume details from marketing copy alone, the best approach is to rely on what the provider actually publishes and what you can test yourself.

Differences and limitations you should expect

Performance varies, even with strong encryption

VPN encryption adds overhead. Depending on protocol choice, server location, and how busy the servers are, you may see slower speeds or higher latency—especially during peak times or if you connect far from your region. Performance also changes when websites actively detect VPN usage and respond with degraded service.

A practical takeaway: treat speed claims as conditional, and focus on how you can measure your own connection.

Not all traffic is equal across apps and networks

Some apps use their own network behaviors (embedded browsers, DNS-over-HTTPS, QUIC/HTTP3, or background sync). Networks like university Wi‑Fi or corporate environments may block VPN connections or restrict certain ports.

This can create a gap between “VPN is on” and “everything is protected and working the way you expect.” Features like kill switches and leak protection reduce risk, but they don’t eliminate every edge case.

Privacy is not the same as perfect anonymity

A VPN changes the path your traffic takes, but it doesn’t erase all identifiers. Devices still have fingerprints, account logins remain personal to the service you sign into, and some traffic metadata can still be observed in different places. If a provider implies absolute privacy, be cautious; evaluate more specific claims and then validate with tests.

Coverage and server availability are not universal guarantees

Even if a provider lists many server locations, real-world accessibility can vary by time, load, and network restrictions. The “best” server for one moment might not be the best the next.

Practical checks you can run

1) Verify tunnel survival and kill switch behavior

Turn on the VPN, then simulate failure (e.g., disconnect Wi‑Fi and reconnect, or temporarily disable the VPN connection). Observe whether internet access continues unprotected when the tunnel is down. If the kill switch is working as intended, traffic should be blocked rather than silently flowing outside the tunnel.

2) Run DNS and IPv6 leak checks

Use online leak test tools in a browser while the VPN is on and off. Compare results for:

  • DNS queries (domain visibility)
  • IP address type (IPv4 vs IPv6)

Interpretation matters: some tests can be inconclusive due to browser settings or the way DNS is cached. Still, consistent differences between VPN-on and VPN-off are a useful sign.

3) Confirm your public IP changes

Check your external IP address (through a reputable “what’s my IP” page) with the VPN enabled. Your IP should typically change relative to when you are not using the VPN.