time to live

each prebroadcast message includes a time to live counter. As a prebroadcast is passed from node to node, each node subtracts one from the counter before passing it on. When a node receives a prebroadcast with a counter that has reached zero, it drops the prebroadcast without forwarding it.

your node uses its time to live setting as a starting value for this counter when sending out prebroadcasts. The time to live setting controls how many nodes in the network are likely to receive your prebroadcasts. Smaller time to live values prevent the message from traveling very far away from your node in the network. Larger starting time to live values will allow your message to reach more nodes but will also increase the load on the network. If you set your starting time to live too high, other nodes in the network may limit your time to live back down to a reasonable value before passing your messages on.

experimental results have shown that setting your starting time to live to a value larger than 10 will not increase the number of nodes you can reach. The optimal value, according to urban legend, is 7.