DNS || Learn all about the Domain Name System || CCNP full Course

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• published: 16 Apr 2016
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First of all don't forget to subscribe for latest update from my channel DNS is vital for internet and networking. To know how DNS is working and how to setup it is essential. I will show you! * Lectures 12 In this course You will learn anything about DNS - Domain Name System. Topic include: *The different components of DNS and how they cooperate. *How the domain hierarchy is structured in different levels. *What different types of information is stored in DNS. *How a DNS query and response works. *How the information is stored in zone files. *Recursive queries, the role of a local resolver. *How to use the tool dig for testing and troubleshooting DNS in various ways.. *We will start with the basics and build ourself up to advanced sections. Starting with the domain hierarchy, how the protocol works and continue into dig, zone transfers and best practices for DNS setup with bind. Introduction to DNS : DNS (Domain Name System) is what drives the internet, without it none of our favourite sites would work, we wouldnt be able to check our email, check our facebook, in fact 99% of internet communications would simply not work without DNS. So what exactly is it? Well essentially DNS is what converts a Domain Name (for example google.com) into a machine readable IP Address. What is an IP Address? - Well its pretty important that you understand what an ip address is if your going to understand how DNS works. Basically every machine that communicates over the internet does so using an IP address. It is a 4 block number that ranges from 0 to 255 for each block, for example: 24.50.10.99 This is an ip address. I will not go into any specific details here but every machine that wants to communicate on the internet uses this address to identity itself. Routers do not understand domain names, they only understand ip addresses so it is essential that a Domain Name converts to one. Note: Above I am referring to IPV4 and not IPv6 So what does DNS do? - Everytime you type in a URL into your web browser your computer has to lookup the ip address of the Domain Name, it does this by doing a DNS lookup. Your computer will query its primary DNS server for the ip address (You can check your primary dns server by going into command prompt and typing ipconfig /all) So far so good right? Well a basic DNS query will typically be a host machine (you for example) asking your primary DNS server for the ip address of google.com, the DNS server will then have the result and return it your machine, your machine now knows where Google is, or at least its ip address which is the information it needs to be able to communicate with it. The hierarchy of DNS - Unfortunately not every DNS server has every result, a full DNS database is enormous, just think about how many millions and millions of websites there are out there! This is why there are several links in the chain for DNS. At the top of the chain are what are called Root Servers, these hold all the answers, they know every single Domain Name that is globally accessible. However your computer will not query these, instead if your primary DNS server does not know the answer it will then ask its next server in the chain, this is typically an ISP DNS server. If this server does not know the answer then it will ask the next one in the chain, this will keep happening until a Root Server is queried which will always have the answer. To speed things up a bit most DNS servers will hold a cache or a temporary store of DNS records, these usually last around 24 hours but they will save the root servers being constantly queried if the DNS server before already knows the answer. So there you have it, a basic introduction to DNS, as I said before it is indeed a massive subject and we've only just scratched the surface here, however you now know what DNS does and why it is so important. For more guides and articles on everything computer related, come check out Stan The Computer Man You may also like to read my related article on how dns works Article Source: http://EzineArticles.com/expert/Cyrus_Jackson/135633 Article Source: http://EzineArticles.com/3381839