NS Lookup

“NSLOOKUP” is not only a cool name for a DNS tool, it is also a very useful tool to gather basic DNS information. It is a Windows tool mainly, as Unix folks tend to prefer other tools. It is a fine tool for scouring Domain Name System (DNS) information. Why use it? For troubleshooting, mainly. What exactly is DNS? An excellent DNS summary comes courtesy of the DNS Resources site:

“The Domain Name System (DNS) is a distributed internet directory service. DNS is used mostly to translate between domain names and IP addresses, and to control email delivery. Most internet services rely on DNS to work. If DNS fails or is too slow, web sites cannot be located and email delivery stalls.” *

That is a nice summary of DNS. That being said, DNS is unfortunately not really that simply. Because all computer related functions and networking technology are in reality based on numbers -or binary or hexadecimal – it follows that addressing on the internet, and in this case a Windows domain/network, are also based on numbers, or binary. If that is true, and it is, then wouldn’t all web site addresses be in numbers? They are in fact based in numbers! They are based in IP addressing, always, no exceptions. However, because most people do not want to memorize and type, for example, http://69.12.152.225 (this web site’s [old] IP address), and because most people do not consider that type of IP address to be aesthetically pleasing, some smart people got together once upon a time to devise a scheme to map or match IP addresses to words or domains: thus www.craigslist.org is used instead of http://66.150.253.241 [example only, although accurate at one point]

You may be wondering: what is so complicated about that? Well, it can get more complicated if you wish, and if you do not believe me, try the DNS related RFCs.

The best analogy I have read or heard is that DNS is the equivalent or is analogous to our residential and business physical addressing scheme, overseen by bureaucracy and, of course, the U.S. Post Office or any country’s postal service as applicable.

A simple ‘nslookup’ example to match this current Azure based domain [subject to change]:

C:\nslookup

Default Server: DNS1.Company.Com
Address: 192.168.125.25

Type in the web site address [enter]:

> riguy.azurewebsites.net

Non-authoritative answer:
Name:    waws-prod-bay-005.cloudapp.net
Address:  23.99.0.12
Aliases:  riguy.azurewebsites.net
          waws-prod-bay-005.vip.azurewebsites.windows.net

Voila, there’s an IP Address associated with the web site.

*More than you ever wanted to know about DNS:

http://www.dns.net/dnsrd/

http://www.dnsreport.com/

http://www.dnsstuff.com

http://www.dns.net/dnsrd/rfc/



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