f. Critical Internet Infrastructure • Interconnected systems and networks, the disruption or destruction of which would have a serious impact on the health, safety, security, or economic well-being of citizens, the provision of essential services, or the effective functioning of government or economy. g. Distributed Denial of Service (DDoS) Attacks • A DDoS attack “is an attempt to make an online service unavailable by overwhelming it with traffic from multiple sources”20. h. Domain Name System (DNS): • A distributed database that allows human-readable names to be translated into IP addresses which are used to identify Internet-connected devices or systems. A query of a DNS server will match a domain name to the IP address required by the computer to route the traffic to its intended destination. i. Fundamental Properties of the Internet (or Internet Invariants) • “Characteristics which have enabled the Internet to serve as a platform for seemingly limitless innovation, outline not only its technology, but also its shape in terms of global impact and social structures”21. These identified characteristics are: voluntary collaboration, open standards, reusable technological building blocks, integrity, permission-free innovation, and global reach. j. Internet Exchange Point (IXP) • A system that allows many Internet-based networks to exchange traffic with each other at a common meeting point, thus eliminating the need to build separate bilateral links with each local network. k. Internet Infrastructure • The elements which make up and enable the movement of usable data across an interconnected network of networks. These elements include protocols and services, software and hardware, network interconnection, communication infrastructure, information, and human resources. l. Internet Service Provider (ISP) • A company or organization that provides individuals, organizations, enterprises and others with access to the Internet. Aside from connecting users, ISPs often provide other services such as email and hosting of websites for their customers. m. Routing • Routing determines how traffic will travel from one point in the network(s) to another. Network nodes that make routing decisions are called routers. Reachability information (i.e. whether a particular network can be reached through a node) is exchanged among the Internet routers. The two types of protocols used to exchange this information are Interior Gateway Protocol used between the routers inside a network (such as OSPF, IS-IS or RIP) and exterior gateway protocol used between networks, or autonomous systems (AS), which is Border Gateway Protocol. One of the vulnerabilities of BGP is that it does not provide means to check the validity of the information exchanged. Such validation requires use of additional tools and practices. n. Stakeholders • The individuals, groups, organizations, entities or communities which have an interest or stake in the Internet. Stakeholders include governments, the private sector, civil society, academia, and the technical community. 20 See http://www.digitalattackmap.com/understanding-ddos/ 21 See https://www.internetsociety.org/internet-invariants-what-really-matters 28 Internet Infrastructure Security Guidelines for Africa internetsociety.org