The Internet is based on a U.S. government project called ________. Today, the Internet is a collection of networks, tied together by common________ . Tier 1 networks form the Internet ________, a system of high-capacity routers and fiber-optic communication links arranged in a(n) ________ topology. Networks that form the Internet are maintained by ________that offer access to consumers. Before data travels over the Internet, it is divided ________ into by a protocol called ________, which also reassembles the data when it reaches its destination. Every device on the Internet uses an IP address ________. addresses are 32 bits long, whereas ________ addresses are 128 bits long, providing billions and billions of possible addresses. Addresses are assigned by ________servers.

IP addresses that are temporarily assigned are called ________ addresses, whereas permanent ones are called ________ addresses. IP addresses cannot be routed over the Internet and are usually assigned to devices within LANs. Because it is difficult to remember IP addresses ________, the name system allocates easy-to-remember domain names. ________level domains include and .edu. The servers that track these names are a vulnerable point in Internet security.