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Hi, guys, and welcome back picking up from where we left off our next stop down the road of having
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a query resolved is top level domain name service.
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We have already seen that in follow the route in the syntax of a domain name.
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And in the district in this lecture, we will see that they do so in the process of name resolution
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to.
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Following up from our previous discussion on the journey of a DNS request, thanks to the root servers
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referral, it is now up to the referred TLT name server to take on the mantle of name resolution and
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take us one step closer to having a query resolved.
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The responsibility of the till the nameserver is simply to provide a referral of its own that will contain
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a server authoritative for the domain we want to browse to.
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In this case, Yahoo.
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At this point, you might wonder why all this back and forth communication.
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If you remember from a previous lecture, DNS uses a hierarchical name architecture with a globally
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distributed system of databases instead of using a flat name architecture featuring a single database
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of information with authority of all domain names and that data.
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Instead, due to the protocols, hierarchical nature, each branch of the tree offers the information
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it has, the root server doesn't know the server hosting WW Dot Yahoo.com.
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But it does know about the code name servers, which is why it previously provided a referral for one.
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In the same manner they're referred to as the nameserver doesn't know about the system hosting www.youtube.com
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either.
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But it does know about the name server responsible for the Yahoo part of the domain to which it is now
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passing the bucket via its own referral.
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In other words, each level of the hierarchy provides a piece of the puzzle needed for the requested
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domain name to be resolved.
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By now, it's probably become clear that most operational aspects of the NSA hierarchical from the way
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domain names are formatted and structured in the downstream, down to the way they are translated when
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browsing.
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So in summary, the main job of the till the nameserver is to pass back a referral with a name server
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that has authority over the requested domain.
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Yahoo in this case.
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There are several categories of till days of which the most important ones to know are generic top level
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domains abbreviated as list and country code, top level domains abbreviated as CC till date.
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Generic top level domains are supposed to reflect the type of industry or space that the organization
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in ownership of that domain falls into.
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For example, it is standard practice for governmental agencies to use the Golf GTI Elite, such as
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the U.S. Golf and for universities to use the EDU- as a University of Oregon does at WW Dot You Oregon
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Dot Edu.
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The original gTLD days were ARPA.
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Com A Aidoo of M. Met and Oak, but the lease has grown bigger with additional fields such as Aero and
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Pro Info and many others joining the group.
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Country code top level domains have been created to allow countries to manage their own namespace and
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make it easier for their citizens to find the resources they need in the languages they understand.
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Greece, Italy, for example, East Asia, Japan's country code, top level domain is cheap and Poland
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is pope.
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Interestingly, countries can also use organizational subdomains within the country code top level domains
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UK, for instance, uses the UK for companies operating in the country, while Australia uses dot com
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dot a--you for its own corporations.
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Other categories of top level domains are still these identical days and utilities since they fall outside
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the mainstream of top level domains.
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We will not go over them in this course, but you are more than welcome to research them in your own
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time.
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The full list of top level domains can be found at HTTPS Kollan Forward Slash Forward Slash W, WW Dot
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I-A and a dot org forward slash domains forward slash route forward slash DB.
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So now with the till the name service assistance, we will proceed to the next lecture to continue our
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journey down the dentistry by contacting the preferred authoritative names of.
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Thank you for watching, guys, and I will see you in the next one.
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