Well, there is no necessity to sit for Network+ certification if you aim for CCNA. CCNA stands for Cisco Certified Network Associate, a very famous Associate level certification in the Network domain. CCNA is much more difficult to pass than CompTIA Network+ certification. Networking professionals take Network+ certification as a stepping stone or as a preparation for CCNA. Clearing Network+ improves your chances of scoring higher in CCNA as your fundamentals will be solid.
Check out the CompTIA Network+ Certification course from Intellipaat and watch the following video on Network Security Tutorial for Beginners.