Net neutrality is a topic that is broadly discussed in economy, politics and technology. Basically, net neutrality states, that all internet packets should be treated equally by Internet Service Providers (ISPs). This principle does, for example, not allow ISPs to treat their own web services or the services of partners better than all other web services. The treatment has to be equal in every aspect - be it connection speed, availability or billing. In this thesis, neither economic nor political aspects of net neutrality are discussed, but the focus is only on technology. For this, a measurement system was built and five internet plans with four Austrian ISPs were ordered. Over a period of two months, over 100,000 single measurement points were taken. Evaluating these measurements showed, for example, that T-Mobile Austria uses a transparent web proxy for HTTP connections and that Hutchison Drei tampers with DNS requests for non-existing domains.