Please explain this internet term like I’m 5 years old.
It’s a phone book. Like what we had in the 90s.
The domain is the person’s name. The Ip address is the phone number.
DNS - a phone book for computers
Can I explain like you’re 75? It’s the phone book. John smith is 555-555-1212.
Similarly, Google.com is easy to remember. http://142.250.72.14/ not so much.
Can I explain like you’re 75
Yes, I could be a 88 year old grandma.
It’s your contact list! But like, for the whole Internet. Type in a name, get the phone number. It works the other way too. Start typing in a number, and it’ll give you the name.
It’s recursive too. When you want to go to domain.tld, you ask your computer, what is the ip address for domain.tld?. If it hasn’t been there yet, or the answer is too old, it asks the next step up, which might be your router. Repeat this process (maybe the router doesn’t know) it might be setup to ask your isp, or a company like quad 9. These companies keep all the records, but even they aren’t authoritative. Whenever they need to, they ask a root server, “which server is in charge of the top level domain .tld?” They get an ip address answer. Then they ask that tld name server, “who is in charge is of domain.tld” and get an answer. Repeat for any subdomains like sub.domain.tld
There are plenty of implementation details (like time to live) but those are the broad strokes.
Numbers are easy for computers to remember, but hard for people to remember. Words are easy for people to remember, but harder for computers to remember.
DNS helps computers and people by translating the easy-to-remember “lemmy.ca” into an IP address for the computer to use and vice-versa.
http://www.r-5.org/files/books/computers/internals/net/Richard_Stevens-TCP-IP_Illustrated-EN.pdf
Just read chapter 11 and don’t rely on summaries.
This is how it works and it’s worth just reading a good bit on it rather than try to think of funny home address / PO box abstractions
The protocols we have studied so far operate using IP addresses to identify the hosts that participate in a distributed application. These addresses (especially IPv6 addresses) are cumbersome for humans to use and remember, so the Internet sup-ports the use of host names to identify hosts, both clients and servers. In order to be used by protocols such as TCP and IP, host names are converted into IP addresses using a process known as name resolution. There are different forms of name reso-lution in the Internet, but the most prevalent and important one uses a distributed database system known as the Domain Name System (DNS) [MD88]. DNS runs as an application on the Internet, using IPv4 or IPv6 (or both). For scalability, DNS names are hierarchical, as are the servers that support name resolution.
DNS is a distributed client/server networked database that is used by TCP/IP applications to map between host names and IP addresses (and vice versa), to pro- vide electronic mail routing information, service naming, and other capabilities. We use the term distributed because no single site on the Internet knows all of the information. Each site (university department, campus, company, or department within a company, for example) maintains its own database of information and runs a server program that other systems across the Internet (clients) can query.
The DNS provides the protocol that allows clients and servers to communicate with each other and also a protocol for allowing servers to exchange information. From an application’s point of view, access to the DNS is through an applica- tion library called a resolver. In general, an application must convert a host name to an IPv4 and/or IPv6 address before it can ask TCP to open a connection or send a unicast datagram using UDP. The TCP and IP protocol implementations know nothing about the DNS; they operate only with the addresses. 511 512 Name Resolution and the Domain Name System (DNS) In this chapter we will take a look at how the names in DNS are set up, how resolvers and servers communicate using the Internet protocols (mainly UDP), and some of the other resolution mechanisms that are used in Internet environments. We do not cover all of the administrative details of running a name server or all of the options available with resolvers and servers. Such information is available from various other sources, including Albitz and Liu’s DNS and BIND text [AL06] and in [RFC6168]. We discuss the details of DNS security (DNSSEC) in Chapter 18.
