Original subtitles

Hi, guys, and welcome to the last lecture of the namespace section where we will discuss authoritative

name service.

The authoritative name server is perhaps the most abstract component of the district and the hardest

one to define, and so we first need to talk about the concept of authority in the DNS protocol and

discuss what it means.

As we've already seen, the DNS namespace is based on a hierarchy of domains.

Linguistically, the term domain refers to a sphere of influence governed by an entity that exercises

authority of the domain and is tasked with certain responsibilities.

In medieval England, for example, a Dutch, it was the domain of a lord who had authority over it,

and he was responsible for managing and protecting that territory.

Nowadays, we often hear people of various professions saying this is outside my domain when asked questions

not related to that trade, indicating that the requests made to them are outside the scope of knowledge.

Conversely, a well-known expert who is very good in their industry is referred to as the leading authority

in that field.

And so that person is responsible for educating the rest of us on their specific subject matter.

Along the same lines, the domain within the context of DNS is a particular slice of the code namespace

where there is somebody with the authority to manage that segment and with a responsibility to provide

answers to the NASA requests made for that very segment.

As a matter of fact, the entire name hierarchy is divided into such segments of authority since, like

we've already discussed, the NSA uses a globally distributed system of databases, and that system

works in conjunction with an equally distributed system of authorities.

This hierarchical authority structure complements the hierarchical known structure in DNS, and it is

not necessary for a different authority to exist at every level of the hierarchy.

As in many cases, a single authority may manage a section of the namespace that spans more than one

level of the structure.

For example, I can is the organization responsible for managing the root servers as well as the entire

top-level domain, while authority over other fields has been delegated to other organizations.

Moreover, as the owner of the school charms dot com domain, I can exercise authority of security trumps

dot com on some of its subdomains like WW dot security charms, dot com and delegate authority to another

organization of a specific subdomain such as Z.Z dot SACU charms dot com.

In short, the authoritative name server is the one holding the DNS name database specific to the requested

domain and the one that will complete the name resolution process by providing the IP address mapped

to the domain name.

We have typed into our browser.

The root server had previously provided a referral because it was not the authoritative server for the

www.youtube.com domain.

Likewise, they referred to Ildy name.

Server was not authoritative for the www.youtube.com domain either, which is why it offered a referral

of its own.

Because of these referrals, we are now at the end of our name resolution journey as we are contacting

the authoritative name server, the house, the information we need.

This time there's not going to be another referral, but a final answer in the form of an IP address

that w w w dot yahoo.com results to so that we can finally browse to that website.

And on that note, we have reached the end of our section on the DNS namespace so far this course,

we have defined the DNS as a protocol, identified its main functions and covered the namespace function

in its entirety by studying the DNS tree, the syntax of the domain name and the purpose of the root

servers, the tilde servers and the authoritative name servers.

Given the knowledge you have acquired thus far, you have no attained the status of intermediate.

Well done for making you up to this point.

And I will see you again in the name resolution section.

Take care.