Handling tough or unexpected technical questions in meetings [closed]

Question

Depending on the project I'm working on, I may be required to attend more meetings with both internal stakeholders or technical management in client companies.

During the course of these meetings, there will inevitably be a few questions crop up that either:

• You do not have an answer to.
• You have not thought about for one reason or another.
• You deem to be irrelevant or completely out of scope of the current meeting.

In each case, how do you answer these questions? Any tips or tricks on remaining authoritative while remaining honest?