When a client asks for a deadline that appears impossible or unrealistic, it is important to maintain clear and upfront communication. Honesty is key in these situations. Additionally, take into consideration the specific circumstances and the client's reaction. Depending on these factors, you might suggest delivering parts of the project by their requested deadline. Lastly, in all your conversations, strive to conclude with questions that encourage the client to share their thoughts and ideas openly, avoiding simple "yes" or "no" responses.