How DNS record Arduino.local works?

I have a question about the Arduino Yun rev2. I attached this board to my local network using the ethernet port. I connected it with static IP address without DHCP and configuring my own local DNS server.

I cannot understand how my local clients can resolve the name arduino.local with the right ip address without inserting its IP in my DNS server.

I can understand this magic while the board uses its own DHCP to attach all other client, but how it works while it has a static IP?

I cannot understand how my local clients can resolve the name arduino.local with the right ip address without inserting its IP in my DNS server.

That's not done in DNS but using a service called mDNS (the Apple world call it Bonjour). Todays PCs have support for it but a simple device which only support DNS won't connect to a "arduino.local" hostname. On the Yun (better on the Linux part of it) a service called avahi is responsible for that functionality.

Clear, thank you for your reply!