DNS servers are a bit like the phone books of the Internet: You can type in “thewirecutter.com,” for instance, and one of the many DNS servers behind the scenes can point you to the IP address of a server hosting the site. Most of the time, your DNS requests automatically route through your ISP, giving the ISP an easy way to monitor your traffic. Some VPN services rely on third-party DNS servers, but the best ones keep DNS servers in-house to prevent your browsing history, or your IP address, from getting out.
To be fair, not all pay VPN services are legitimate, either. It's important to be careful who you choose. Over on ZDNet's sister site, CNET, I've put together an always up-to-date directory of quality VPN providers. To be fair, some are better than others (and that's reflected in their ratings). But all are legitimate companies that provide quality service.
This is important to understand. Consumer VPN services protect your transmission from your location to their location, not from your location all the way to the destination application you're using. If you think about it, this makes sense: A consumer VPN service is operated by a completely different company than, for example, Facebook or your bank.
You want to skip PPTP if at all possible. It’s a very dated protocol that uses weak encryption and due to security issues should be considered compromised. It might be good enough to secure your non-essential web browsing at a coffee shop (e.g. to keep the shopkeeper’s son from sniffing your passwords), but it’s not up to snuff for serious security. Although L2TP/IPsec is a significant improvements over PPTP, it lacks the speed and the open security audits found with OpenVPN.
An OSPF-routed network can be subdivided into areas, which are collections of contiguous networks. All areas are connected together through a common area called the backbone area. A router that connects an area to the backbone area is called an area border router (ABR). Normally, ABRs have a physical connection to the backbone area. When it is not possible or practical to have an ABR physically connected to the backbone area, administrators can use a virtual link to connect the ABR to the backbone.
Supported Client Software Android, Chrome, Firefox, iOS, Linux, macOS, Windows Android, Chrome, iOS, Linux, macOS, Windows Android, Chrome, iOS, macOS, Opera, Windows Android, iOS, Linux, macOS, Windows Android, ChromeOS, iOS, Linux, macOS, Windows Android, iOS, Linux, macOS, Windows Android, iOS, macOS, Windows Android, iOS, macOS, Windows Android, Chrome, Firefox, iOS, Linux, macOS, Windows Android, iOS, macOS, Windows