- Nameserver holds a sorted list of (hostname, peer, container id, ip) tuples.
- Entries are gossiped using topology gossip / broadcast - only new/updated entries
are propogated as expected.
- Entries for a given peer are removed when the connection to the peer is lost.
- Entries are tombstoned when containers die. Tombstones are kept for 10mins,
as they do not need to survive partition, only gossip propagation delay.
- use 'host' to lookup MX record. It's shorter
- use getent everywhere else for dns lookups, instead of dig; this
tests more of the o/s name resolution machinery and is generally
shorter.
- introduce assert_dns_record helper that performs forward and reverse
- lookup introduce some vars for holding constants, so we don't have
to repeat them
Marc CARRE