Are apsd, ntpd, mDNSResponder, trustd, netbiosd necessary for macOS functioning?
apsd - Used for FaceTime push notifications

ntpd - Used to synchronize clock

mDNSResponder - Part of the Bonjour protocol, used to scan your network for other Bonjour-enabled devices (printers, computers, etc...)

trustd - Used for validating SSL certificates

netbiosd - Used when interacting with Microsoft shared drives

This is all normal activity. However, if you are worried about security, you can disable the services you don't plan on using.

Edit: You might not want to disable ntpd and trustd as they are necessary for basic functionality such as browsing websites.