Basically, there are 4 sections in the online test. aptitude section is compulsory for everyone; the remaining 3 sections are analog, digital, and embedded software. We can choose any sections we want. The above 3 sections are not compulsory for everyone so I choose both analog and digital sections. Questions asked in the analog section are pretty tricky and also some questions are lengthy. the analog section covers topics like OPAMPs, Rc-Circuits(very important), MOSFETs, BJTs, and Diode circuits .one should practice a lot of questions from the above topics I prefer sedra smith and gate questions for practice and also listen to Razavi lectures(electronics-1 playlist) in youtube. those lectures are very well explained by Razavi himself (these lectures are very important for a basic understanding of analog electronics; he is a masterpiece If I can say in one word).
In the Digital section questions are asked from topics like counters,8086 microcontroller, pipeline registers, setup time, Hold Time, Verilog, and FSM. etc questions are pretty easy basic concepts are required.I prefer Bhima Shankar sir lectures from the Kreatryx channel(https://youtube.com/playlist?list=PLs5_Rtf2P2r77kmBnXAe06RsI3VadeQ5s Follow this playlist ) and practice previous year gate questions.