Most VPN services allow you to connect to servers in many different countries. In our VPN directory, we list both the number of servers the service maintains, as well as the number of countries. By default, you'll usually be assigned a server in your home country, but if you want to obfuscate your location, you may want to connect to a server in a different country.
When a VPN connection drops, you might just lose your connection. But because the internet is very good at routing around failures, what is more likely to happen is your computer will reconnect to the internet application, simply bypassing the VPN service. That means that -- on failure -- your local IP address may "leak out" and be logged by the internet application, and your data may be open to local Wi-Fi hackers at your hotel or wherever you're doing your computing.
If you're of the iPhone persuasion, there are a few other caveats to consider for a mobile VPN. Some iPhone VPN apps don't use OpenVPN, even if the VPN service that made the app supports the protocol. That's because Apple requires additional vetting if a company wants to include OpenVPN with its app. VPN app developers have slowly started jumping through those extra hoops and are bringing support for protocols such as OpenVPN to iOS.
When we looked at just iPhone VPNs last year, our results yielded a very different breakdown. In our tests on iOS, we found that Hide My Ass, Golden Frog Vypr VPN, KeepSolid VPN Unlimited, NordVPN, and PureVPN were the top performers. Hide My Ass and PureVPN dominated in the download speed tests, improving speeds by 10.1 and 6.8 percent, respectively.
When you download a file from a server without a VPN, there’s a chance you will encounter network congestion, most likely on your nearby ISP network or at the download server itself. When you use a VPN service, you add a third potential bottleneck to the route. Whether because of server load or congestion on the network surrounding the server, there’s a higher chance that your speed will be affected while connected to a VPN.
IPSec – Internet Protocol Security (IPSec) can be utilized with Layer 2 Tunneling Protocol (L2TP) or Internet Key Exchange version 2 (IKEv2). While it is not open source, it does do well in the performance category and can be used natively (without apps) on most operating systems. IPSec/IKEv2 may be the best protocol to use with some mobile devices (iOS), which do not work as well with OpenVPN.
Voluntary tunneling occurs when a client computer or routing server creates a virtual connection to the target tunnel server. To accomplish this, tunneling client software and the appropriate tunneling protocol must be installed on the client computer. For the protocols discussed in this technical reference, voluntary tunnels require an IP connection (either LAN or dial-up).
Anti-Malware/Anti-Spyware Features: Using a VPN doesn’t mean you’re invulnerable. You should still make sure you’re using HTTPS whenever possible, and you should still be careful about what you download. Some VPN service providers—especially mobile ones—bundle their clients with anti-malware scanners to make sure you’re not downloading viruses or trojans. When you’re shopping, see if the providers you’re interested in offer anti-malware protection while you’re connected. For example, previously mentioned Hotspot Shield offers malware protection to its premium users. It may not be a dealbreaker for you, but it’s always good to have someone watching your back.

VPN services, while tremendously helpful, are not foolproof. There's no magic bullet (or magic armor) when it comes to security. A determined adversary can almost always breach your defenses in one way or another. Using a VPN can't help if you unwisely download ransomware on a visit to the Dark Web, or if you foolishly give up your data to a phishing attack.
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