[~]$ ping 126.96.36.199 PING 188.8.131.52 (184.108.40.206): 56 data bytes 64 bytes from 192.168.0.103: icmp_seq=0 ttl=64 time=62.978 ms 64 bytes from 192.168.0.108: icmp_seq=0 ttl=64 time=0.077 ms
Why is Retrospect communicating with address 220.127.116.11?
Address 18.104.22.168 does not refer to any node on your network. It is our Class D multicast address, assigned to Retrospect by the Internet Assigned Numbers Authority and listed in their registration database at:
Sending a packet to a multicast address is how Retrospect locates its clients using our Piton Name Service.
IANA’s assignment of port 497 to "Dantz" (Retrospect) is listed on their site at:
There should be no traffic on the Internet using port 497 that’s not using Retrospect.
Why does this appear to be an IP address off site?
Multicast makes for a very simple and clean way to easily determine a group of available clients in a single operation. Multicast is setup using the multicast IP address 22.214.171.124 (which corresponds to the all hosts group on the subnet) and the router effectively handles getting the information out to the hosts on the subnet. This is the most effective way to find clients.
See more information on IGMP multicast model.
How to ensure your device is reachable via multicast
You can test what devices are reachable via multicast using the
ping tool on Mac or Windows.
Windows — Open Command Prompt and run:
Mac — Open Terminal and run:
For both, you should see an output similar to the one below. Each IP address corresponds to a device that is multicast-enabled and accessible.
Last Update: November 10, 2015