305 Unit 3 Disscussion

advantages of using the a DNS pseudo root in a Linux server. Introduction DNS, or the Domain Name System, is an integral part of how systems connect with each other to communicate on the internet. Without DNS, computers, and the people who use them, would be required to connect using only numerical addresses known as IP addresses. Besides the obvious problem of having to remember a large number of complex numbers for simple tasks, communicating through IP addresses also causes some additional problems. Moving your website to a different hosting provider, or moving your servers to different locations would require you to inform every client of the new location. DNS servers, the computers that together form the system that allow us to use names instead of addresses, can server many different functions, each of which can contribute to your ability to accessing servers by name. In a previous guide we discussed some of the basic terminology and concepts of the domain name system. We will assume some familiarity with the concepts covered in that article. In this guide, we will talk about some of the different types of DNS server setups and what the advantages, use cases, and properties are of each. The Path of a DNS Query When a client program wants to access a server by its domain name, it must find out how to translate the domain name into an actual routable address that it can use to communicate. It needs to know this information in order to get or send information to the server. Some applications, including most web browsers, maintain an internal cache of recent queries. This is the first place the application will check, if it has this capability, in order to find the IP address of the domain in question. If it does not find the answer to its question here, it then asks the system resolver to find out what the address of the domain name is. A resolver in general is any component that acts as a client-side participant in a DNS query. The system resolver is the resolving library that your operating system uses to seek out the answer for DNS queries. In general, system resolvers are usually what we consider stub resolvers because they are not capable of much complexity beyond searching a few static files on the system (like the /etc/hosts file) and forwarding requests to another resolver. So generally, a query goes from the client application to the system resolver, where it is then passed to a DNS server that it has the address for. This DNS server is called a recursive DNS server. A recursive server is a DNS server that is configured to query other DNS servers until it finds the answer to the question. It will either return the answer or an error message to the client (the system resolver in this case, which will, in turn, pass it to the client application). Recursive servers generally maintain a cache as well. It will check this cache first to see if it already has the answer to the query. If it does not, it will see if it has the address to any of the servers that control the upper level domain components. So if the request is for www.example.com and it cannot find that host address in its cache, it will see if it has the address of the name servers for example.com and if necessary, com. It will then send a query to the name server of most specific domain component it can find in order to query for more information. If it does not find the address to any of these domain components, it has to start from the very top of the hierarchy by querying the root name servers. The root servers know the addresses of all of the TLD (top level domain) name servers which control zones for .com, .net, .org, etc. It will ask the root servers if it knows the address of to www.example.com. The root server will refer the recursive server to the name servers for...

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