All India services
Indian Administrative Service (IAS), Indian Police Service (IPS), Indian Forest Services (IFS)
Group “A” services
Indian Foreign Service (IFS), Taxation related: Indian Revenue Service (IRS): 1. Customs and Excise; 2. Income Tax, Corporate related: Corporate Law Service (ICLS), Indian Trade Service (ITS)
Accounts-related: 1. Audit & Accounts service 2. Civil Accounts 3. Railway Accounts
4. Defense Accounts 5. Post & Telecom Accounts & Finance.
Communication-related: 1. Postal Service 2. Information Service (IIS)
Railways: 1. Traffic service 2. Personnel service 3. Railway Protection Force
Defence: 1. Ordinance factory (Administrative) 2. Defense Estate service
Group “B” Services
Armed forces headquarters, Delhi, Andaman & Nicobar Islands, Lakshadweep, Daman & Diu and Dadra & Nagar Haveli 1. Civil service (DANICS) and 2. Police Services (DANIPS), Pondicherry: 1. civil service 2. Police service
If you want to become an officer in any of the above services, you’ve to clear this exam’s three stages viz. 1) prelim 2) mains 3) interview, then depending on your merit, preference and vacancies you’ll get the allotment.