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Hi, guys, and welcome to the last lecture of the namespace section where we will discuss authoritative
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name service.
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The authoritative name server is perhaps the most abstract component of the district and the hardest
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one to define, and so we first need to talk about the concept of authority in the DNS protocol and
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discuss what it means.
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As we've already seen, the DNS namespace is based on a hierarchy of domains.
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Linguistically, the term domain refers to a sphere of influence governed by an entity that exercises
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authority of the domain and is tasked with certain responsibilities.
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In medieval England, for example, a Dutch, it was the domain of a lord who had authority over it,
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and he was responsible for managing and protecting that territory.
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Nowadays, we often hear people of various professions saying this is outside my domain when asked questions
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not related to that trade, indicating that the requests made to them are outside the scope of knowledge.
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Conversely, a well-known expert who is very good in their industry is referred to as the leading authority
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in that field.
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And so that person is responsible for educating the rest of us on their specific subject matter.
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Along the same lines, the domain within the context of DNS is a particular slice of the code namespace
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where there is somebody with the authority to manage that segment and with a responsibility to provide
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answers to the NASA requests made for that very segment.
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As a matter of fact, the entire name hierarchy is divided into such segments of authority since, like
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we've already discussed, the NSA uses a globally distributed system of databases, and that system
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works in conjunction with an equally distributed system of authorities.
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This hierarchical authority structure complements the hierarchical known structure in DNS, and it is
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not necessary for a different authority to exist at every level of the hierarchy.
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As in many cases, a single authority may manage a section of the namespace that spans more than one
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level of the structure.
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For example, I can is the organization responsible for managing the root servers as well as the entire
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top-level domain, while authority over other fields has been delegated to other organizations.
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Moreover, as the owner of the school charms dot com domain, I can exercise authority of security trumps
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dot com on some of its subdomains like WW dot security charms, dot com and delegate authority to another
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organization of a specific subdomain such as Z.Z dot SACU charms dot com.
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In short, the authoritative name server is the one holding the DNS name database specific to the requested
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domain and the one that will complete the name resolution process by providing the IP address mapped
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to the domain name.
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We have typed into our browser.
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The root server had previously provided a referral because it was not the authoritative server for the
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www.youtube.com domain.
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Likewise, they referred to Ildy name.
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Server was not authoritative for the www.youtube.com domain either, which is why it offered a referral
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of its own.
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Because of these referrals, we are now at the end of our name resolution journey as we are contacting
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the authoritative name server, the house, the information we need.
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This time there's not going to be another referral, but a final answer in the form of an IP address
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that w w w dot yahoo.com results to so that we can finally browse to that website.
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And on that note, we have reached the end of our section on the DNS namespace so far this course,
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we have defined the DNS as a protocol, identified its main functions and covered the namespace function
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in its entirety by studying the DNS tree, the syntax of the domain name and the purpose of the root
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servers, the tilde servers and the authoritative name servers.
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Given the knowledge you have acquired thus far, you have no attained the status of intermediate.
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Well done for making you up to this point.
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And I will see you again in the name resolution section.
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Take care.
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