I will tell you the type of job perform by Indian Forest Service officer so that you can remember and I have idea.

Here I’m telling you some duties perform by them

Protecting and preserving rich heritage of forest resources .

This includes preventing illegal logging of trees, poaching of animals etc

To implement National forest policy framed by MoEF from time to time.

Devise plans for legal commercial exploitation like timber etc

Ranks
Grade Union Ministry Designation
Apex Scale Director General of Forests
HAG+ Scale Additional Director General of Forests
Higher Administrative Grade Inspector General of Forests
PB-4 Additional Inspector General of Forests
PB-4 Deputy Inspector General of Forests
PB-4 Director
PB-3 Assistant Inspector General of Forests
Apex Scale Principal Chief Conservator of Forests
Higher Administrative Grade Additional Principal Chief Conservator of Forests
PB-4 Chief Conservator of Forests
Regional Chief Conservator of Forests
PB-4 Conservator of Forests
PB-3 Deputy Conservator of Forests
Divisional Forest Officer
PB-3 Probationary Officer

Deputations
As per Rule 6 of the Indian Forest Service (Cadre) Rules, 1966 deputation of IFS officers broadly falls into two categories:
Central Deputation
State Deputation

For Central Deputation, there are two schemes devised for the purpose of regulating appointments in Government of India and organisations under its control.
Central Staffing Scheme
Non-Central Staffing Scheme