Which aerodromes are in the scope of ICAO recommendations?
Which aerodromes are in the scope of ICAO recommendations?

Per Annex 14, international airports only, and preferably any public use airport—


  1.3.1 As of 27 November 2003, States shall certify aerodromes used for international operations in accordance with the specifications contained in this Annex as well as other relevant ICAO specifications through an appropriate regulatory framework.
  
  1.3.2 Recommendation.— States should certify aerodromes open to public use in accordance with these specifications as well as other relevant ICAO specifications through an appropriate regulatory framework.


(Emphasis not mine.)



If for any reason, a country deviates from the standards, it needs to notify ICAO.

How do I know whether such aerodrome in a given country benefit from ICAO recommendations?

Deviations are published by ICAO in Supplements to each Annex. I can't speak for 3.9.6 due to paywalls. However, here are examples for Canada's deviations to Annex 14—


  
  Canada does not provide runway end safety areas but does provide a 60 m graded strip beyond the runway end. (More on that story.)
  Canada computes runway longitudinal slopes by dividing the difference between the maximum and minimum runway end elevation by the runway length.
  


Below (may not be current due to paywalls) are countries that fully adhere to Annex 14—


  Contracting States which have notified ICAO that no differences exist:
  
  
  Colombia
  Egypt
  Georgia
  Ghana
  Ireland
  Malaysia
  Monaco
  Namibia
  Peru
  Sri Lanka
  United Republic of Tanzania