HBASE-1675, JSharp has posted logs where a temporary DNS outage does his cluster a death blow.
When cluster members report in, the master composes the regionserver name by doing a hostname lookup and appending it to port and startcode passed over by the regionserver. The host lookup during a DNS outage when from name to IP. Master then thought this regionserver an unknown host and told it restart.... and so on.
If the regionserver composed its name once, it could pass this the master and avoid a DNS lookup per regionserver report.