Home | Site Map           
   
     

Fun with DNS: Three Useful Commands


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 Small Business Web Hosting provides the essential tools for using the Web as a marketing tool. The package includes web hosting, the StreamSend permission-based email marketing solution. Please email questions or comments about this article to articles@ezpublishing.com. Thank you.


MORE RESOURCES:

Yahoo! News Search Results for URL
Yahoo! News Search Results for URL

E-mail URL http://
Ukrainian Festival, Sunday, September 12, starts at 12:00 p.m. 3275 Elmwood Ave, Kenmore to celebrate cultural and ethnic heritage and traditions. Entertainment includes Ukrainian dance groups from Rochester, live music form Toronto, theme basket and raffles, children?s activities, and church tours.
SAJADAH TERAKHIR KARYA EDY A EFFENDI: SEBUAH ANALISIS SEMIOTIK MICHAEL RIFATERRE
BAB st1:*{behavior:url(#ieooui) }
MS probes mystery IE bug
URL shortening shenanigans Microsoft is investigating reports of a new bug in Internet Explorer.?
Nokia N8 launches September 30, says senior manager
digg_url = ' (function() { var s = document.createElement('SCRIPT'), s1 = document.getElementsByTagName('SCRIPT')[0]; s.type = 'text/javascript'; s.async = true; s.src = 'http://widgets.digg.com/buttons.js'; s1.parentNode.insertBefore(s, s1); })(); Digg '; Tapani Kaskinen is Nokia's Senior Comms Manager, so it's fitting that he'd be the first person from the company to ...
Google Power User Tips: SERP URL Parameters
In Part 1, we looked at query operators for refining our searches. Now for Part 2, let?s look at parameters that we can add/modify in the URL of the the Google SERP (search engine results page.)
Twitter's link logging will be a boon for businesses
Twitter is getting into analytics. Finally. This week, the microblogging service announced that it will be updating its URL shortener t.co to help alleviate malware problems and track link sharing on its service.
Dating in the Dark: Muscles and Manhandling
This week on ABC?s Dating on the Dark, the contestants learn that a person?s voice sometimes doesn?t match their body. Who will end up finding a spark in the dark? The guys (from left to right in the photo below): Chad, 33, works in catering and is a good ol? Texan at heart. Kyle, 25, is a [...] SHARETHIS.addEntry({ title: "Dating in the Dark: Muscles and Manhandling", url: "http ...
Top Chef: Producer Laughs Off Emmy Fall
On what was a shining moment for Bravo?s Top Chef as the show took home an Emmy Award, one of the show?s producers took a fall as she got up to head down the aisle. Erica Ross is not upset about all the videos circulating the web about her fall, but instead she laughs it [...] SHARETHIS.addEntry({ title: "Top Chef: Producer Laughs Off Emmy Fall", url: "http://realitytvmagazine ...
Dancing With The Stars: Bristol Palin Denies Diva Rumors
Bristol Palin has recently been deemed the diva of season eleven on Dancing With the Stars on ABC, with some even referring to her as the next Kate Gosselin. But according to Bristol, she is not being difficult or acting like a diva in any way. Keep reading to hear what she has to say! While [...] SHARETHIS.addEntry({ title: "Dancing With The Stars: Bristol Palin Denies Diva Rumors", url ...
The Biggest Loser: Meet Season Ten?s Contestants
If you are anticipating the return of The Biggest Loser on NBC, here is your chance to get a quick look at the season ten contestants. I am sure most of you are wondering whether or not there will be a contestant heavier than Michael Ventrella, the heaviest contestant in the history of the show?well, [...] SHARETHIS.addEntry({ title: "The Biggest Loser: Meet Season Ten?s Contestants", url ...

 

 

Foto Log | Perfect Laptop | Webdesign Place

Copyright © 2008 All Rights Reserved URLMaster.com