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فيديو شرح Getting Started with Domain Name System (DNS) Network Fundamentals Part 17 ضمن كورس اساسيات الشبكات شرح قناة Network Direction، الفديو رقم 18 مجانى معتمد اونلاين
Getting Started with Domain Name System (DNS) Network Fundamentals Part 17
The Domain Name System (DNS) is the elegant system used for, among other things, resolving a name to an IP address.
Think about when you put a web address into a web browser. That needs to be converted to an IP address, so the client will send the DNS server a lookup message, and the DNS server will send a response.
DNS servers contain zones, which is a container for all the information for a domain. If a DNS server has a zone for a domain, it is authoritative for that domain. If it is non-authoritative, it can make its own query, and send it to another DNS server.
Inside the zone are records. These contain the information such as name to IP mappings. This particular type is called a host or ‘A’ record. Other types include a pointer (PTR), which is the reverse of the host record, the canonical name (CNAME), which is an alias, and the Mail Exchange (MX) record, which holds a list of mail servers.
When a server can’t answer a request on its own, it needs to ask another DNS server for help. One option is to configure another server as a forwarder. The server performs a recursive query, where it finds a record on the client’s behalf.
The alternative is to use root hints, where the server asks other servers for hints about where the authoritative DNS server is located. It does this using recursive queries
Quiz: link: https://networkdirection.net/labsandquizzes/quizzes/quiz-dns/
Patreon information: https://networkdirection.net/patreon/
For more information on the DNS process, I highly recommend: https://www.cloudflare.com/learning/dns/what-is-dns/
Overview of this video:
0:00 Introduction
0:36 The Domain Name Space
2:10 Zones and Records
4:32 Record Types
6:10 A Simple Lookup Process
9:31 Using Forwarders
10:58 Using Root Hints
12:58 Quiz
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