I am trying to download rhel7 kernel code using git as follows.

$ git clone  https://git.centos.org/git/rpms/kernel.git
Cloning into 'kernel'...
fatal: unable to access 'https://git.centos.org/git/rpms/kernel.git/': gnutls_handshake() warning: The server name sent was not recognized
$ git clone  git://git.centos.org/git/rpms/kernel.git
Cloning into 'kernel'...
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.