I wanted to know what's difference between the point of presence(PoP) and access point(AP). Are APs grouped under PoP? The same question goes to a domain and autonomous system(AS), do multiple domain belong to one AS? what's their multiplicity relationship(one-one, many-one, many-many)?

A picture of physical deployment in the internet would be strongly appreciated!

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The term "Point of Presence" (POP) is a telecommunications industry term that seems to predate the rise of the commercial Internet, for a location where two or more telephone companies' lines interconnect. For example, where a local phone company interconnects with long distance carriers. This term became more well-known to the public in the days of dial-up Internet in the mid to late 1990's as the place where dial-up ISPs would connect their modems and PPP servers to the local phone company's lines. Dial-up ISPs would give their customers a list of phone numbers for modem pool hunt-groups at various POPs, and it was up to the customers to make sure they were using a dial-up number for a POP that was within their local free calling area.

In the context of major Internet network providers, a Network Access Point is an outdated name for an Internet Exchange Point (IXP). It's a building (or floor or room of a building) where major network providers connect their networks to each other. So it's like a POP, but POP is an older term from the POTS/PSTN era, and is still more about telephone networks and private wide area data lines, whereas NAP and IXP are more an Internet-backbone-centric term.

In terms of Internet networking, the term "domain" is really only used in the context of the Domain Name System (DNS). It's a name that a company (or person, or other entity) can own, and use as the base name for all of that company's Internet hosts (servers) and services. If you own a domain name, you can have any host name within that domain point to any IP address you want. So if your company's web server is hosted at some commercial hosting facility, you can still point www.example.com at the IP address that your hosting company assigned to your server, even though it's not an IP address from the range your ISP assigned to your company.

An Autonomous System is a company (or other organization) network that isn't dependent on a single ISP for Internet connectivity and public IP address space. If you want to be able to "own" your own IP address space, and have routes into your network from more than one ISP, you need to become an Autonomous System.

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