Hi Hameed, RHCE should be starting point as you will learn alot here about basic networking,Firewalls and all other OS related stuff.
To do CCNA, basic understanding of these basics is necessary.How to configure ip,subnets and what are gateways can be learnt here. Even if you are doing CCNA, you should understand how to setup the labs with different OS level features. I prefer first doing System Administration before moving on to CCNA and CCNP. Thanks, Narender Rao
