Trivia – difference b/w Central, state and all india service officer

Was reading it up at quora… found this…. abhi tak to mujhe pata bhi nahi tha…

There are broadly three types of government officers in India.

1: Central Government Officers

These officers are appointed by the Government of India and they work with a department (cadre) of the Government of India. The appointing authority is the President of India. These officers are appointed by the UPSC. The examples of such officers are IRS, IFS, IRTS who are appointed through Civil Services Examinations; IES, MES officers appointed through Engineering Services Examinations. They can work in State Government or in other Ministries of Central Government on deputation on equivalent rank.
They can be removed/dismissed by the Government of India.

2: State Government Officers

These officers are appointed through the State Public Service Commission by the State Governments. The appointing authority is the Governor of the State. The officers like PCS, BDO, AEE etc. are appointed as State service officers. They can be dismissed/removed by State Government.
They can also be promoted to All India Service (AIS) by UPSC/Government of India.

3: All India Service (AIS) officers

There are three AIS in India at present viz. IAS, IPS and IFoS (Indian Forest Service). These officers are appointed by the Government of India, but they work under the State Government.

Each AIS officer is allotted a cadre (State), where they work for life. However, they can work with Central Government or other State Government on deputation.

These officers can’t be removed by State Governments, which can only suspend them. The final decision to remove the officer lies with Central Government.

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1. Can IAS officers work in different state as well?
2. State officer can become IAS. How long does it take?