Hi,

when I am updateing by apt-get update,
The following error is occured.


W: GPG error: http://10.3.100.149 unstable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 07DC563D1F41B907
W: Failed to fetch http://security.debian.org/dists/len...es/Release.gpg Could not resolve 'security.debian.org'

W: Failed to fetch http://security.debian.org/dists/len...tion-en_IN.bz2 Could not resolve 'security.debian.org'

W: Failed to fetch http://security.debian.org/dists/len...tion-en_IN.bz2 Could not resolve 'security.debian.org'

W: Failed to fetch http://volatile.debian.org/debian-vo...le/Release.gpg Could not resolve 'volatile.debian.org'

W: Failed to fetch http://volatile.debian.org/debian-vo...tion-en_IN.bz2 Could not resolve 'volatile.debian.org'

W: Failed to fetch http://volatile.debian.org/debian-vo...tion-en_IN.bz2 Could not resolve 'volatile.debian.org'

W: Some index files failed to download, they have been ignored, or old ones used instead.
W: You may want to run apt-get update to correct these problems

Please help me how to overcome the problem

if you're looking at updating the gpg keys then-

gpg --keyserver hkp://wwwkeys.eu.pgp.net --recv-keys PUBKEY
gpg --armor --export PUBKEY | apt-key add -

if you're not able to resolve the names, then you should look at your /etc/resolv.conf to see if your nameservers are in there.