Hardware & Networking

Hi Anvay,
Good to see that you have an interest in Ethical Hacking and Security profession in early days.
However, to become a white hat hacker to work with a company to safeguard their infrastructure and intellectual property from internal or external threat you need to go through professional course like Ethical Hacking. Later on you may get a certification from EC council.
It's not necessary to get certified by CISEH and CPTE but important is CEH for EC council and if possible CISSP. These two courses cover all kind of hacking related technologies, skills and processes. It's up to you if you would like to get certifications of CISEH and CPTE.
Another Important aspect is you need to understand first about Infrastructure and different areas like Computing, Storage and Networking and how they have put together to run an IT. In early stages you might be curious about EH but in reality you need to earn expertise, experience towards when and where you are going to apply what EH knowledge.

Hi Srinivas,
Mentioned all three are in a good demand in their own field but the common factor is Skill, Expertise and Experience to be considered to become a successful professional.
Now, if I will about the overall situation then DevOps will be the future but here to answer your question precisely the availability of DBA professional either Oracle and SQL is less than other two. Also, if you begin your career in DBA then, later on, you may move to Big Data, Business Intelligence as a career.
Whereas, you will find a good competition in Networking because a number of candidates are more.
Development has many branches and you need to decide which path you need to follow. As per current market trends as well as in future demand Java, Angular Js, Node Js, Python, Jquery and Apex would help you a lot in Cloud computing back-end programming and IoT.