Original subtitles

Hi, guys, and welcome to the first lecture of the namespace section in this module, we will go over

the anatomy of a typical domain name and break it down into its individual components.

This is by far one of the most important lectures in this course, as it sets the foundational knowledge

required to follow the rest of the material.

If you are completely new to most of the information we're going to cover, I would highly recommend

that you go over this video list twice, taking as many notes along the way as possible.

We will start examining the domain four months from right to left, because that is the direction that

a domain name is interpreted.

What I mean by that is contrary to the way we type a domain name into a browser from left to right.

For instance, w WW dot example dot com domain names are interpreted by DNS the other way around, from

right to left.

I know that this probably doesn't make much sense to you right now, but it will do later on the course.

The first component for domainname starting from right to left is the route represented by a dot.

This is a very special dot and not to be confused with any other dots, this dot is in fact so dominant

that nothing else can take its place, meaning that the rightmost component of a domain name can only

be the route represented by this dot and nothing else to the end.

Think of the route as a component in the domain name, just so you don't confuse the special dot with

other dots being present.

After the route comes, the top level domain abbreviated as till date, we will not go into depth until

dates at this stage, since there's going to be an entire module dedicated to two days further down

the line.

But it should be pointed out that comm is just one of a plethora of TLDs that you can come across.

The reason why I have chosen this particular field for this demonstration is because it's one of the

most popular ones, and so chances are you can recognize it even if you do not have any previous experience

with DNS.

Other well-known fields, I could have very easily taken up this spot, net org, Io and many others.

What follows a top-level domain is the second level domain, which in this case is example for simplicity

sake.

The second level domain, along with a top level domain, make the zone apex otherwise known as naked

domain or apex domain.

Finally, the third level domain is usually something like W W W, which is more of a naming convention

rather than a necessity, as you could very easily replace it with BBB, CCC or any other arbitrary

string of characters.

If it came down to creating a domain name for, say, your website.

The components of a domain name are known as labels, with a route being said to have a label of no.

Each label is a subdomain of its parent domain.

For instance, W WW is a subdomain of examiner.com, while example is a subdomain of the com top-level

domain.

The entire domain name stretching all the way from the route down to the third level domain is known

as the fully qualified domain name abbreviated as F and which is the absolute reference to a domain

name.

Important to note that the student is not the same thing as a euro, as a euro contains the domain name

of a site, as well as other information, including the transfer protocol and the path, for example,

in the Euro Europe's column forward slash forward slash w WW dot example dot com forward slash learning

forward slash w WW dot example dot com is the domain name, while hedge DPS is the protocol and forward

slash learning.

Forward Slash is the path to a specific page on the website.

A portion of a domain name, such as the House portion of the WWE W Dot Examiner.com domain is known

as a partially qualified domain name abbreviated as PCDI, and a partially qualified domain name starts

with a hostname, but it may not reach up to the root.

Finally, it is important to note that the reason why the dots representing the route is colored differently

to the other dots is because the first is a special dot, while the other dots serve as the limiters

separating the labels of a domain.

Before finishing off this lecture here, a few more things to keep in mind in relation to the syntax

of a domain name.

The first one is that each label can be up to 63 characters long.

The characters allowed and labels can be a through z uppercase a lowercase digits from zero all the

way to nine and hyphen.

This rule is known as the LDH rule letters.

Digits hyphen labels may not start or end with a hyphen.

An additional rule requires a top level domain.

Names should not be old numeric.

Last but not least, there is no maximum limit on the number of subdomains.

In our example, we only went up to third level domain, but it could just as easily have a 4th level

domain, 5th level domain, etc..

However, a domain name in society can be up to 255 characters in total, including the dots.

That's everything for this lecture, everybody.

Thank you for watching, and I'll see you in the next one.