Are apsd, ntpd, mDNSResponder, trustd, netbiosd necessary for macOS functioning?

Question

I'm seeing 5 processes with network activity ( sending/receiving bytes ). I'm not sure whether these are normal occurrences?

List of processes

• apsd
• ntpd
• mDNSResponder
• trustd
• netbiosd

I researched a few of those and some were associated to file sharing via windows or bonjour, however I don't have any other PCs on my network to even begin sharing files with.

Answer 1

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.

Answer 2

Originally, in Mac OS X 10.2 in 2002, the central purpose of mDNSResponder was to respond to Multicast DNS requests. Nowadays mDNSResponder is responsible for Unicast DNS as well as Multicast DNS, for both hostname lookups and service discovery. It also manages other networking functions, like “Wake for network access”. Disabling mDNSResponder would break a number of networking functions, not least the ability to use DNS hostnames in URLs when using a web browser, and would most likely render the device unbootable.