As you want to get the Indian Administrative Service preparation tips for Interview so here it is for you:

Some useful tips for a successful interview at UPSC are:
To have a positive body language
To have a good personal turnout and ensuring the right posture
To answer questions clearly and confidently
Try to remain calm and composed even when faced with provocative questions
Try not getting into long winded explanations and answer to the point.

Here is a list of Basic framework of what question should be prepared:
About yourself

What is your roll number?
Tell me about yourself?
What is your height/weight/age etc.?(these are trying to make you fumble….keep cool)
What is the meaning of your name or surname?
Famous persons having same birthday or year
Why you want to join civil services?
Why your first preference is IAS or IPS or IFS?

About your College

Refresh your knowledge about the branch of your graduation. Also update your awareness about recent developments in your branch.
Collect information about the university/institute where you are graduated from?
Collect information about UPSC members, their service and cadre
You can also expect some questions regarding your optional subject
Why you have chosen this optional?
Why you want join even after higher education. Don’t you think you should contribute in your field of specialization? (If you have done post graduation or Ph.D.)
Why don’t you continue in research? (If you are from science background)

About your place

Collect complete information about your home state or state of residence, in following sectors:

History
Politics
Culture
Tourism
General statistics (census 2011)
Recent developments and current affairs
Personalities
Development
Social problems

Here are some example questions:

What is special about your place? (village/city/district/state)
Tourist or historical places around your native place?
Tell me five positives and negatives about your place? (native place/district/state/place of graduation)
What are the major problems in your district/state?
Historical importance of your native place/any place in your city?
General statistics about your district/state? – population, population density, literacy, economic importance, health etc.
Famous personalities of your state and district? (in the field of art, literature, sports, social workers and leaders)
List chief ministers of different states? (Especially North Eastern states)

About your hobbies

Collect complete information about your hobbies…

Personalities associated with the hobby
Importance of your hobby
Information about it in historical perspective
Your activities related your hobby
Benefits of your hobby
Sometimes there will be some unexpected questions regarding your sports interests. They may say “Oh! You play volleyball, then I’ll ask about basketball/cricket”. A sweet smile is sufficient to deal with such questions.