The DNS is a distributed, hierarchical database where authority flows from the top (or root) of the hierarchy downward.
When thinking of the structure of the DNS, imagine an inverted tree. Each branch of the tree is within a zone of authority; however, multiple branches of the tree can be within a single zone.
The software (Bind being the most common) that stores domain name information is called a domain name server. A single name server can be authoritative for multiple zones. All zones have a primary master and a secondary master name server that provides authoritative responses for their zones.
If you query a name server not authoritative for a particular zone, that name server will most likely have up-to-date information. This is because zone information propagates throughout the Internet at regular intervals, and name servers cache zone information for which they are not authoritative.
DNS Commands
There are three crucial commands that can put all the DNS information you need at your fingertips. The way to use this article is to try each of the commands listed on a domain name, so you can see what the output looks like. Learn by doing!
Zone file database records divide DNS information into three primary types: NS (Name Server) records, MX (Mail Exchange) records, and A (Address) records. NS records indicate the name servers. MX records indicate the hosts that handle e-mail delivery; the priority (pri) number indicates the order in which mail servers are used, with the lowest number receiving the highest priority. The A (Address) records map hostnames to IP addresses, the real names of machines.
host
This is the simplest of the DNS commands. It is a quick way to determine the IP address of a hostname:
: host www.your-domain-name.com
The -a option will return all of the DNS information in verbose format.
: host -a www.your-domain-name.com
Now that you know the IP address for www.your-domain-name.com, try a reverse lookup.
: host IP-ADDRESS
dig (domain information groper)
This command gathers and returns DNS information in a format the name server can use directly. You will find it easy to query specific name servers with dig.
You can quickly determine the Name servers of your host or any other host:
: dig ns your-host.com
Then you check your (or another) website against the host's name servers:
: dig www.your-domain-name.com @ns.your-host.com
Dig can provide output that is in the same format as the zone file itself. Here is how to get the whole zone file:
: dig any your-domain-name.com
Here are the most useful dig query types: dig any (gathers all DNS information), dig ns (gathers name server information), dig mx (gathers mail exchanger information) and dig a (gathers network address information).
The dig command can also do reverse lookups with output formatted for the zone file:
: dig -x IP-Address
nslookup
You can use this tool as a single line command, or you can use it interactively, which distinguishes it from the other DNS commands. Once you have started nslookup, type set all to list the default options. As with dig you can choose the server (name server) you want to query, and you can decide the type of DNS information on which to focus.
Just as you can issue commands to nslookup interactively, you can also change the initial defaults by starting a .nslookuprc file. The format of the .nslookup is one command per line:
set type=NS
set domain=srvns.your-host.com
set timeout=10
Conclusion
These three commands can provide you with most of the information you need about your domain names. They are powerful tools, and this article should provide you enough information to get started or offer a quick refresher if you already use these commands.
About the Author:
Dan Forootan founded ez publishing, inc. in 1998. EZ Publishing's ez publishing, inc. provides the essential tools for using the Web as a marketing tool. The package includes web hosting, the ez publishing, inc. solution. Please email questions or comments about this article to ez publishing, inc.. Thank you.
tidy up service Northbrook ..When it comes to web hosting, the quality of the... Read More
Choosing the right web server will be one of the... Read More
Web hosting services play a vital part in your website's... Read More
Bandwidth explained:Bandwidth is the amount of data transfer that you... Read More
Dedicated web hosting has its difficulties and problems from time... Read More
If you're looking for a professionally designed web site at... Read More
First of all, some people are worried that they will... Read More
When talking about free anything the legitimate question that first... Read More
Many online entrepreneurs these days are faced with the problem... Read More
Bandwidth in its simplest terms refers to the amount of... Read More
If you have ever used EBay then you know how... Read More
With literally hundreds of web hosting providers competing for your... Read More
The next concern for you after designing and developing web... Read More
First things First. Why would you like to have Windows... Read More
Every website needs a great web host, however when you... Read More
As a web host reseller, one of your most important... Read More
After you have spent some time and creativity on designing... Read More
Once you have considered the design for your website and... Read More
The ProblemToo often new webmasters sign-up with the first good... Read More
The first thing that you must realize when looking for... Read More
Knowing when it is time to move onto a dedicated... Read More
What sort of web hosting options should you go for... Read More
The main thing wrong today with trying to find a... Read More
Virtually anyone with an email address knows what Spam is,... Read More
When looking for a Web Host there are lots of... Read More
reliable home cleaners Buffalo Grove ..There are literally hundreds of thousands of web hosting companies... Read More
Your new website is ready to upload, and now you... Read More
Reseller Defined:The term Reseller according to the dictionary means to... Read More
You've already got a website, but your current hosting provider... Read More
Bandwidth in its simplest terms refers to the amount of... Read More
There are many attributes that makes a web hosting provider... Read More
Although we are aware of Linux adoption by large enterprises,... Read More
Deciding how to host your ecommerce Web site and what... Read More
If you're reading this article, you might be interested in... Read More
With plethora of hosting companies offering services, choosing a good... Read More
Whether you are disgruntled with the level of service your... Read More
If you're looking for a professionally designed web site at... Read More
Many online entrepreneurs these days are faced with the problem... Read More
Why is dedicated hosting such a big hit on the... Read More
If you are anything like me, you'd probably like to... Read More
First, to see if you can use cheap web hosting... Read More
First of all we must determine the meaning of the... Read More
"Bargains for sale, Unlimited Hosting for only a Dollar.""Get your... Read More
Professional web designers don't come cheap. A good web designer... Read More
This article is meant to all who already have a... Read More
Many people think that all web hosts offer the same... Read More
Some web hosts are offering more than others for the... Read More
Most Internet service providers do not give you static IP... Read More
Indeed, choosing a right web hosting service for your website... Read More
Every website needs a great web host, however when you... Read More
Web Hosting |