Through ASDM i checked the time of our firewall it shows may2003. I want to fix this but i am afraid if i did this asa5510 setting may go away or something else will happen. Does the time matter on firewall and should i change it?
It is a good idea to have the correct time.
If you're using digital certificates or time-based ACLs or any feature based on time, it is required that the time is set up correctly.
Also very helpful for logging and troubleshooting.
However, it is not mandatory to have the ASA with the right time to have it operational.