The minimum educational qualification for IES is an engineering degree and an engineering graduate from any branch can apply and qualify IES.
However, the syllabus of IES does not have computer science in the list of subjects.
Hence, a computer engineer can apply but has to choose a branch paper from the following.
Thus, selecting from the above-mentioned subject can be tricky for a computer engineer. Before applying, you should study the syllabus properly and then choose the subject according to your interests and knowledge. Electrical Engineering can be an easy branch paper. One of my seniors was from Mineral Engineering and wrote his IES branch paper on Electrical and got selected.
You can appear in the examination, provided you have secured at least 50% in your engineering degree. Choose your branch paper carefully.