I need to change the my hosts' NIC speed and duplex setting from Auto Negotiate to 1000Mb Full duplex. is it possible to do it through script. I have 100s of Hosts in my vcenter.
You can use several methods.
esxcli network nic set -n vmnic# -S speed -D duplex
esxcfg-nics -s 1000 -d full vmnic1
Both commands can be execute remotely from VMA or vcli.
Another possibility is to use powercli.
More info about powercli way is at https://communities.vmware.com/thread/164721