t reg- istries (RIRs), for the Europe region (each RIR manages IP addresses and autonomous system numbers in its own region). The RIPE Atlas is in fact a global network of hard- ware probes (small hardware devices that are connected to an Ethernet port on the router at users' premises) and anchors (enhanced RIPE Atlas probes that have big- ger measurement capacity), which perform active quality measurements. Anyone can access this data via Internet traffic maps, streaming data visualizations, and via an API. RIPE Atlas measurement nodes (probes and anchors) perform built-in measurements which include ping for measuring of RTT delay, traceroute for measuring the hop distance (and possibly number of ASs on the packets' path, based on IP addresses of router interfaces), DNS, and HTTP (with or without SSL/TLS - secure sockets layer/transport layer security). As typical for a measurement platform, users can also define their customized measurements. SamKnows - Internet Performance Measurement. This is a distributed network of whiteboxes (i.e. probes, as outlined in Figure 7.12) for Internet QoS measurements [30], which are placed in consumers' homes to measure the performance of fixed broadband access. They are controlled by servers that do scheduling of measurement tests and send the data to centralized databases. Besides the built-in performance measurements, the SamKnows platform is designed to provide flexibility for future modifications or enhancements (when they will be required). Primary quality metrics for SamKnows are given in Table 7.10. Overall, all measurement tools and platforms typically use active measurements, where the probes (hardware or software-based) generate additional traffic (for QoS measurement purposes) in addition to the user traffic. For example, the measurement of the bitrate (by using HTTP file download and upload, for measurement of downlink and uplink speeds, respectively) requires larger file sizes for higher bitrates. For example, SamKnows for fixed broadband access requires file size