Original subtitles

Hi, guys, and welcome back, having talked about the composition of a domain name, we will now proceed

to discussing the context in which domain names exist only on the coasts.

We compare DNS with a phonebook in the sense that names are mapped to numbers.

That is where the similarities between a phone book and DNS.

And however, and I will now expand on that.

In the first case, a phone book is used as a single authority, a central database of all available

names and their associated numbers within a specific geographic region.

Consequently, all users of that specific region would need to obtain a copy of that database.

This is an example of what we call flat name architecture, where there is no sophisticated internal

structure and no clear relationships between the names themselves exist.

In the case of Dennis, on the other hand, having a central database of all available domain names

of the entire internet along with their IP addresses, that each of those names translates to is simply

not feasible for several reasons.

The first reason would be the administrative overhead involved in managing every possible domain name

in the internet.

Another reason would be that the flat name architectures that work with a central database did not scale

well to name systems containing hundreds of thousands of machines.

Another important reason would be that it's extremely difficult to ensure that domain names are unique

across the entire namespace.

Given these challenges, the designers of the NSA came up with the ingenious decision to move away from

the flat name approach and adopt hierarchical name architecture, whereby a multiple level structure

is used to organize names in a specific way and within the structure a particular device is can be determined

by looking at its name as a result, instead of having a singular database of domain names.

We have a globally distributed collection of databases forming a tree like structure that is indexed

by domain names and where each domain name is essentially just a path in that large tree.

In this globally distributed name, system administration is decentralized completely, and delegation

is handed over to organizations, allowing this way many authorities to share in the registration and

administrative process and take over the responsibility of managing their own data.

By the same token, every organization administering a domain can further divided into subdomains,

and each subdomain can in turn be delegated to other organizations, which are then entitled to change

the data freely and even divide those subdomains into more subdomains and delegate those.

Benefits.

Decentralised administration, thanks to its ability to delegate authority to organizations, so easy

management flexibility as it allows a namespace to scale and the internet to grow.

And the guarantee that every domain name is unique.

The district consists of the root name servers are the top, followed by the top level domain name servers,

followed by authoritative name servers.

In the next lecture, we're going to study the root name servers and the important role they play in

the DNS namespace.

Thank you for watching, guys, and I will see you in the next one.