My ubuntu 11.04 guest is not able to connect to the internet when launched as -net user. Any help is much appreciated.

qemu command line
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amitava@bonjovi:/var/vms$ qemu-system-x86_64 -m 512 -drive index=0,media=disk,if=virtio,file=ub2.qcow2,boot=on -vnc :0 -monitor stdio -net nic,model=virtio,vlan=1 -net user,vlan=1,hostname=ubuntu2

ifconfig output in guest
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amitava@ubuntu2:~$ ifconfig eth0
eth0      Link encap:Ethernet HWaddr 52:54:00:12:34:56
          inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe12:3456/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:11 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1984 (1.9 KB) TX bytes:1748 (1.7 KB)

amitava@ubuntu2:~$ nslookup google
Server:        10.0.2.3
Address:    10.0.2.3#53

Non-authoritative answer:
Name:    google.com
Address: 74.125.115.104
Name:    google.com
Address: 74.125.115.106
Name:    google.com
Address: 74.125.115.105
Name:    google.com
Address: 74.125.115.147
Name:    google.com
Address: 74.125.115.103
Name:    google.com
Address: 74.125.115.99

amitava@ubuntu2:~$ traceroute google.com
traceroute to google.com (74.125.115.99), 30 hops max, 60 byte packets
1 10.0.2.2 (10.0.2.2) 0.469 ms 0.457 ms 0.453 ms
2 * * *
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Here's the host info
==============
amitava@bonjovi:~$ uname -a
Linux bonjovi 2.6.32-32-server #62-Ubuntu SMP Wed Apr 20 22:07:43 UTC 2011 x86_64 GNU/Linux

amitava@bonjovi:~$ qemu-system-x86_64 --version
QEMU PC emulator version 0.12.3 (qemu-kvm-0.12.3), Copyright (c) 2003-2008 Fabrice Bellard

Thank you,
Amitava