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When the EVE-OS 'downloader' module is instructed to download an image for another App on the device from the data-store, if the App's data-store configuration has the FQDN in the '.local' domain, it knows this data-store is local to the EVE device. The 'downloader' module will send out mDNS query packets on all the internal bridges to multicast address 224.0.0.251 and port 5353 to ask for service information. Since the local data-store App is on one of those bridges, and the App is running 'Avahi' and is configured to respond to those mDNS queries, it will reply on the bridge to the EVE-OS side with the service running on it's host-name and IP address. The 'downloader' module needs to match the host-name in the reply to the data-store FQDN string, and in this example it is 'ubuntu-4321-http-server', and get the IP address from the reply, e.g. 10.1.0.5, and this IP address will be used for the TCP/IP endpoint of downloading the image. The 'downloader' module will use the URL of 'http:/10.1.0.5' in replacing the FQDN string defined in the data-store configuration and it finds the source IP address on the same internal bridge for the local endpoint of connection. The IP address of the local data-store App can change after reload but this local downloading functionality works the same.
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