DNS Terminology

let's go over some terminology that you're gonna hear when we're talking about DNS the first one is root and root is the way we pronounce the very top of this DNS hierarchy we spell it with a dot but we pronounce it as root the next one is TLD which stands for top-level domain and they are the ones that are in this level here right below the root of the hierarchy there are ones like com net edu UK and there's others that you've heard about like gov or net but a whole bunch of the country ones like dot JP for Japan US for United States plus some ones you may not have really heard about like dot info dot biz and so forth another one another term is f q-- d n which stands for fully qualified domain name and a fully qualified domain name is one that's completely spelled out like let's take this point right here this this one down here there's ASP MX it's fully qualified domain name is ASP M X dot l dot google.com dot and this last dot here comes from the root of the DNS hierarchy so when we spell out the entire domain name starting from the bottom and working our way all the way to the top use each one of these names as we go up the tree and then we also include the one at the very end the dot here now when you're browsing the web and sending emails you've probably never put that dot in there and usually a computer puts it in there for you so you don't to worry about it but as we start playing with some of the DNS tools and setting up our own domains we're going to find that it's important to include that dot at the end another term is host a host is a point in this tree that refers to a specific computer this tree is built up of all these names organized in a in a structure like this but not all of these are actually computers like like you write here that that's not an actual computer that's just the top of a domain name however this point like this right here www you calm that might be an actual computer and so this is a host but the distinction is really kind of fuzzy because there can be also a host like here at yahoo.com there could be an actual computer responding to requests at this point is also a domain so so like I said the the distinction is kind of a little fuzzy but you'll hear people referring to things like host names or domain names and usually they means that as domain name is kind of like somewhere in the middle this tree and a host name is down here at the bottom but it's easy to kind of mix them up so of course along with hosts we need to include domain and also throw in sub domain and a sub domain is merely just a domain that's below some other domain like here this L right here in the tree is the L is a sub domain of the google.com domain so this is the L sub domain and there are sub domains all over in this tree here like CS is a sub domain of the UCSD edu domain but you know UCSD is a sub domain of the edu domain and edu is a sub domain of the the root so so it's really there's no difference between a sub domain or domain except kind of to explain to someone else that either talking about one point in the tree or some point that's below in the tree so those are some of the basic terminologies there's a root we've got TLD top-level domain we've got fully qualified domain name where if qdn got host domain and sub to me you

Channel: Barry Brown

Views: 45,371

Keywords: dns, computer science

Id: vPyaAfc95bM

Length: 4min 13sec (253 seconds)

Published: Sun Jun 24 2012