What do you mean by GATE? Is it an online exam?

GATE- Graduate Aptitude Test for Engineering.
 Yes, it is a National level Examination.
The Graduate Aptitude Test in Engineering (GATE) is an examination that primarily tests the comprehensive understanding of various undergraduate subjects in engineering and science. GATE is conducted jointly by the IISc and seven IITs.
The following students are eligible to take GATE:[6]
Bachelor's degree holders in Engineering / Technology / Architecture (4 years after 10+2/ Post-B.Sc./ Post-Diploma) and those who are in the final year of such programs.
Master's degree holders in any branch of Science/Mathematics/Statistics/Computer Applications or equivalent and those who are in the final year of such programs.
Candidates in the second or higher year of Four-year integrated master's degree programs (Post-B.Sc.) in Engineering / Technology.
Candidates in the fourth or higher year of Five-year integrated master's degree programs or Dual Degree programs in Engineering / Technology.
Candidates with qualifications obtained through examinations conducted by professional societies recognized by UPSC/AICTE (e.g. AMIE by iE(i), AMICE(i) by the institute of Civil Engineers (India)-iCE(i)) as equivalent to B.E./B.Tech