DNS Resolution

The Internet maintains two principal namespaces: the domain name hierarchy and the IP address system.The Domain Name System maintains the domain namespace and provides translation services between these two namespaces. Internet name servers implement the Domain Name System. The top hierarchy of the Domain Name System is served by the root name servers maintained by delegation by the Internet Corporation for Assigned Names and Numbers (ICANN) 

Most common services of a DNS server:

• Standard Name Resolution: Taking a DNS name as input and determining its corresponding IP address.
• Reverse Name Resolution: Taking an IP address and determining what name is associated with it.
• Electronic Mail Resolution: Determining where to send electronic mail (e-mail) messages based on the e-mail address used in a message.

Steps involved in DNS resolution:

1. Web Browser checks in the local dns cache.
2. Else, the DNS resolver request will be sent to DNS server by Internet Service Provider.
3. DNS servers communicate recursively to get the IP address for the Domain Name being look up

How to clear DNS cache on a Windows machine? Use ipconfig /flushdns command

How to view DNS cache on a Windows machine?

C:\Users\bharathi>ipconfig /displaydns

Windows IP Configuration

clients4.google.com
—————————————-
Record Name . . . . . : clients4.google.com
Record Type . . . . . : 5
Time To Live . . . . : 26
Data Length . . . . . : 8
Section . . . . . . . : Answer
CNAME Record . . . . : clients.l.google.co
apis.google.com
—————————————-
Record Name . . . . . : apis.google.com
Record Type . . . . . : 5
Time To Live . . . . : 194
Data Length . . . . . : 8
Section . . . . . . . : Answer
CNAME Record . . . . : plus.l.google.com
clients1.google.co.in
—————————————-
Record Name . . . . . : clients1.google.co.
Record Type . . . . . : 5
Time To Live . . . . : 135
Data Length . . . . . : 8
Section . . . . . . . : Answer
CNAME Record . . . . : clients-cctld.l.goo

plus.google.com

—————————————-
Record Name . . . . . : plus.google.com
Record Type . . . . . : 1
Time To Live . . . . : 62
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.34
Record Name . . . . . : plus.google.com
Record Type . . . . . : 1
Time To Live . . . . : 62
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.33
Record Name . . . . . : plus.google.com
Record Type . . . . . : 1
Time To Live . . . . : 62
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.38
Record Name . . . . . : plus.google.com
Record Type . . . . . : 1
Time To Live . . . . : 62
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.41
Record Name . . . . . : plus.google.com
Record Type . . . . . : 1
Time To Live . . . . : 62
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.46

http://www.google.co.in

—————————————-
Record Name . . . . . : http://www.google.co.in
Record Type . . . . . : 1
Time To Live . . . . : 255
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 74.125.236.63

C:\>tracert http://www.google.com

Tracing route to http://www.google.com [74.125.236.211]
over a maximum of 30 hops:

1 1 ms 1 ms 1 ms 192.168.1.1
2 3 ms 2 ms 2 ms ras.beamtele.net [183.83.0.1]
3 3 ms 5 ms 4 ms ras.beamtele.net [183.82.14.1]
4 20 ms 19 ms 34 ms ras.beamtele.net [183.82.14.57]
5 17 ms 15 ms 16 ms 72.14.194.18
6 18 ms 16 ms 16 ms 66.249.94.170
7 17 ms 16 ms 18 ms 72.14.232.110
8 18 ms 17 ms 17 ms 209.85.240.147
9 17 ms 16 ms 16 ms maa03s17-in-f19.1e100.net [74.125.236.211]

Trace complete.

C:\>nslookup http://www.facebook.com
Server: UnKnown
Address: 192.168.1.1

Non-authoritative answer:
Name: star.c10r.facebook.com
Addresses: 2a03:2880:f00c:800:face:b00c:0:1
31.13.79.49
Aliases: http://www.facebook.com

References:

1. http://igoro.com/archive/what-really-happens-when-you-navigate-to-a-url/
2. http://en.wikipedia.org/wiki/Domain_name
3. http://technet.microsoft.com/en-us/library/cc775637(v=ws.10).aspx
4. http://www.bytemark.co.uk/support/technical_documents/dnsworks
5. http://www.tcpipguide.com/