Table of Contents

## What can I use instead of PPTP?

Alternatives to PPTP

- OpenVPN. OpenVPN is our recommended VPN protocol.
- L2TP/IPSec. Second to OpenVPN, L2TP/IPSec is a strong runner-up for the best VPN protocol.
- SSTP. Like PPTP, Microsoft developed SSTP.
- IKEv2. This protocol is even less common than SSTP, and is another brainchild of Cisco and Microsoft.

**Which VPN has PPTP?**

ExpressVPN. A titan in the VPN market, ExpressVPN has everything you might need from a VPN service. Its server network covers 160 locations in 94 countries, easily unblocks streaming platform libraries, and offers a wide range of protocols, including PPTP.

### What is the difference between max flow and Min cost flow?

The min cost flow problem also has special nodes, called supply nodes or demand nodes, which are similar to the source and sink in the max flow problem. Material is transported from supply nodes to demand nodes.

**What is minimum-cost maximum-flow problem?**

This task is called minimum-cost flow problem. Sometimes the task is given a little differently: you want to find the maximum flow, and among all maximal flows we want to find the one with the least cost. This is called the minimum-cost maximum-flow problem.

#### What is the relationship between maximum and minimum cost circulation?

All the maximum ﬂows use (t,s) at the same capacity, so they use the edge (t,s) at the same cost. This means that the minimum cost circulation has to be minimum cost on the section from s to t, which makes the max-ﬂow also min-cost.

**How do you solve the minimum cost flow problem?**

This is achieved by setting the lower bound on all edges to zero, and then making an extra edge from the sink . The following problems are special cases of the minimum cost flow problem (we provide brief sketches of each applicable reduction, in turn):