You can't know everything and don't need to know everything.
What I offer is a lot of knowledge for the core items I currently use (Dynamics CRM, C#, Javascript, SQL) and a very broad set of knowledge based on 20 years of been there done that seen what happens if you do it that way...
The requirement of any contractor (or consultant) is to convey a sense of competency / trustworthiness that allows the interviewer to believe you either fit the exact requirements or provide enough additional value (in my case 20 odd years of battle wounds and stories of utter disasters) that you are the person who will add the most value....
What I offer is a lot of knowledge for the core items I currently use (Dynamics CRM, C#, Javascript, SQL) and a very broad set of knowledge based on 20 years of been there done that seen what happens if you do it that way...
The requirement of any contractor (or consultant) is to convey a sense of competency / trustworthiness that allows the interviewer to believe you either fit the exact requirements or provide enough additional value (in my case 20 odd years of battle wounds and stories of utter disasters) that you are the person who will add the most value....