DNS – Domain Name Service

DNS makes the internet work. You use it every day when you type www.google.com and find yourself on the google website. It takes the name you type and returns the ip address. Without that ip address, it would be like using the telephone without a telephone number. You would get a dial tone but not much else. Think of it like an information service like 411 where you can ask for the telephone number. A technical presentation by Mike Warfield on Robust DNS is one of the best I have seen to date. Highly recommended reading if you want to learn more about how the everything works.

References

DNS Best Practice Resources – http://www.infoblox.com/library/dns_resources.cfm
Secure BIND Template – http://www.cymru.com/Documents/secure-bind-template.html
RFC 1912: “Common DNS Operational and Configuration Errors”– ftp://ftp.rfc-editor.org/in-notes/rfc1912.txt
RFC 2182, “Selection and Operation of Secondary DNS Servers”– ftp://ftp.rfc-editor.org/in-notes/rfc2182.txt
Microsoft Web site outages highlight DNS as single point of failure– http://www.infoworld.com/articles/hn/xml/01/01/26/010126hndnsfailure.html
DSL outage hits AT&T in Southeast– http://www.cnn.com/2007/TECH/12/04/att.outage.ap/index.html
OpenDNSsec:– http://www.opendnssec.org

If you are interested to see this inside windows, try the ipconfig command with the /displaydns or /flushdns options.

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\jad>ipconfig /displaydns

Windows IP Configuration

         hp000d9d1d8228
         ----------------------------------------
         Record Name . . . . . : HP000D9D1D8228
         Record Type . . . . . : 1
         Time To Live  . . . . : 439694
         Data Length . . . . . : 4
         Section . . . . . . . : Answer
         A (Host) Record . . . : 192.168.168.27


         1.0.0.127.in-addr.arpa
         ----------------------------------------
         Record Name . . . . . : 1.0.0.127.in-addr.arpa.
         Record Type . . . . . : 12
         Time To Live  . . . . : 439694
         Data Length . . . . . : 4
         Section . . . . . . . : Answer
         PTR Record  . . . . . : localhost


         27.168.168.192.in-addr.arpa
         ----------------------------------------
         Record Name . . . . . : 27.168.168.192.in-addr.arpa.
         Record Type . . . . . : 12
         Time To Live  . . . . : 439694
         Data Length . . . . . : 4
         Section . . . . . . . : Answer
         PTR Record  . . . . . : HP000D9D1D8228


         localhost
         ----------------------------------------
         Record Name . . . . . : localhost
         Record Type . . . . . : 1
         Time To Live  . . . . : 439694
         Data Length . . . . . : 4
         Section . . . . . . . : Answer
         A (Host) Record . . . : 127.0.0.1

If you are interested in how these responses get to you and their routers, this is an excellent link to play with.

http://www.traceroute.org/

These are a few good links to play and learn about about DNS.

look up the root servers associated with the domain. Hint: dig @’www’ ‘marlin.ab.ca’ ‘SOA’ +trace

graphical view of a domains delegated name servers