It's upon their qualification and experience and knowledge
Internal job postings, references, walk ins, websites.
Internal job posting.
Hr is good internal job postings are also fine but bosses hire noneligible ones without ethics to build business..
Through references and job portals.
3 rounds of interview- HR - Business inetrview- Domain interview
Its upon there qualification
Through Referral or Consultancy..
First interview then eligible candidate is hired