I have gone through a lot of links available on internet to fix the issue of Ubuntu VM unable to access internet, but I found no solution. I use this laptop in my office (not from home). It could be specific to my environment, therefore I am creating this question here. Following are the details.

Problem Statement:

1) Ubuntu VM is unable to connect to internet. (eg. Can’t connect to www.google.com)

2) Ubuntu VM is able to connect to Host and thus able to browse web sites internal
to the company.

I have the following software on my Office Laptop.

1) OS Windows 7 Professional. (Host)

2) Oracle VirtualBox Version 4.3.2.

3) Ubuntu 12.04 Desktop LTS Virtual Machine (Guest)

The VirtualBox network setup for Ubuntu VM is as below:

Adapter 1

Attached to : “NAT”

Name: no name

Advanced

Adapter Type: Intel PRO/1000 MT Desktop (82540EM)

Promiscuous Mode: Allow VMS

MCA Address: 080027E2E304

Cable Connected is ticked

There is no port forwarding

Adapter 2

Attached to: Host-only Adapter

Name: VirtualBox Host-Only Ethernet Adapter

Advanced

Adapter Type: Intel PRO/1000 MT Desktop (82540EM)

Promiscuous Mode: Allow VMS

MCA Address: 080027B5740B

Cable Connected is ticked

There is no port forwarding

The guest is able to ping host and host is also able to ping guest. This could be the reason why guest is able to only access internal web sites. The main problem is guest is not able to browse web sites external to the office, i.e it cannot connect to internet.
Following is the ifconfig output from ubuntu.

eth0

      Link encap:Ethernet  HWaddr 08:00:27:e2:e3:04



      inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0



      inet6 addr: fe80::a00:27ff:fee2:e304/64 Scope:Link



      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1



      RX packets:99 errors:0 dropped:0 overruns:0 frame:0



      TX packets:291 errors:0 dropped:0 overruns:0 carrier:0



      collisions:0 txqueuelen:1000 



      RX bytes:17115 (17.1 KB)  TX bytes:33151 (33.1 KB)

eth1

       Link encap:Ethernet  HWaddr 08:00:27:b5:74:0b  



      inet addr:192.168.56.101  Bcast:192.168.56.255  Mask:255.255.255.0



      inet6 addr: fe80::a00:27ff:feb5:740b/64 Scope:Link



      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1



      RX packets:10 errors:0 dropped:0 overruns:0 frame:0



      TX packets:65 errors:0 dropped:0 overruns:0 carrier:0



      collisions:0 txqueuelen:1000 



      RX bytes:3848 (3.8 KB)  TX bytes:11496 (11.4 KB)

lo

      Link encap:Local Loopback  



      inet addr:127.0.0.1  Mask:255.0.0.0



      inet6 addr: ::1/128 Scope:Host



      UP LOOPBACK RUNNING  MTU:16436  Metric:1



      RX packets:119 errors:0 dropped:0 overruns:0 frame:0



      TX packets:119 errors:0 dropped:0 overruns:0 carrier:0



      collisions:0 txqueuelen:0 



      RX bytes:15122 (15.1 KB)  TX bytes:15122 (15.1 KB)