Gossip - how is the reply to a request calculated

[njd42]

• Do we need to make multiple / repeat requests idempotent?
• What 'entropy' should be present in the responses?
• Should we gossip those known to be ledger peers at all?
  • note that we can't take an IP address and determine if it is a ledger [reverse lookups just don't work]
  • not sharing our ledger peers could help with DDoS resistance