Original subtitles

Hi, guys, and welcome back picking up from where we left off our next stop down the road of having

a query resolved is top level domain name service.

We have already seen that in follow the route in the syntax of a domain name.

And in the district in this lecture, we will see that they do so in the process of name resolution

to.

Following up from our previous discussion on the journey of a DNS request, thanks to the root servers

referral, it is now up to the referred TLT name server to take on the mantle of name resolution and

take us one step closer to having a query resolved.

The responsibility of the till the nameserver is simply to provide a referral of its own that will contain

a server authoritative for the domain we want to browse to.

In this case, Yahoo.

At this point, you might wonder why all this back and forth communication.

If you remember from a previous lecture, DNS uses a hierarchical name architecture with a globally

distributed system of databases instead of using a flat name architecture featuring a single database

of information with authority of all domain names and that data.

Instead, due to the protocols, hierarchical nature, each branch of the tree offers the information

it has, the root server doesn't know the server hosting WW Dot Yahoo.com.

But it does know about the code name servers, which is why it previously provided a referral for one.

In the same manner they're referred to as the nameserver doesn't know about the system hosting www.youtube.com

either.

But it does know about the name server responsible for the Yahoo part of the domain to which it is now

passing the bucket via its own referral.

In other words, each level of the hierarchy provides a piece of the puzzle needed for the requested

domain name to be resolved.

By now, it's probably become clear that most operational aspects of the NSA hierarchical from the way

domain names are formatted and structured in the downstream, down to the way they are translated when

browsing.

So in summary, the main job of the till the nameserver is to pass back a referral with a name server

that has authority over the requested domain.

Yahoo in this case.

There are several categories of till days of which the most important ones to know are generic top level

domains abbreviated as list and country code, top level domains abbreviated as CC till date.

Generic top level domains are supposed to reflect the type of industry or space that the organization

in ownership of that domain falls into.

For example, it is standard practice for governmental agencies to use the Golf GTI Elite, such as

the U.S. Golf and for universities to use the EDU- as a University of Oregon does at WW Dot You Oregon

Dot Edu.

The original gTLD days were ARPA.

Com A Aidoo of M. Met and Oak, but the lease has grown bigger with additional fields such as Aero and

Pro Info and many others joining the group.

Country code top level domains have been created to allow countries to manage their own namespace and

make it easier for their citizens to find the resources they need in the languages they understand.

Greece, Italy, for example, East Asia, Japan's country code, top level domain is cheap and Poland

is pope.

Interestingly, countries can also use organizational subdomains within the country code top level domains

UK, for instance, uses the UK for companies operating in the country, while Australia uses dot com

dot a--you for its own corporations.

Other categories of top level domains are still these identical days and utilities since they fall outside

the mainstream of top level domains.

We will not go over them in this course, but you are more than welcome to research them in your own

time.

The full list of top level domains can be found at HTTPS Kollan Forward Slash Forward Slash W, WW Dot

I-A and a dot org forward slash domains forward slash route forward slash DB.

So now with the till the name service assistance, we will proceed to the next lecture to continue our

journey down the dentistry by contacting the preferred authoritative names of.

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