dns interface configuration re: hbase

[Greg Bledsoe <gr...@personal.com>]

Greetings

This is more of a hadoop question, and if so I can take this over there, but as I am most interested in hbase-specific information, I thought it best to try here first, I appreciate your patience…

We've had trouble with name resolution affecting hadoop and hbase, and have paired the configuration down to allow only dns and match forward and reverse lookups to hostname with no aliases and this seems to have resolved most of the issues, but one question remains.   In hadoop configuration there is a configuration item, "dfs.datanode.dns.inerface" which takes the name of an interface.  It seems this is not required to be configured and would be irrelevant on a single-homed server.  In the case where you have an external and internal interface, like Amazon or Rackspace type environments, and your dns servers in resolv.conf are routed through one or the other, why would you need this parameter?  Is it necessary and does it have any benefit or impact on hbase?

Thanks

Greg Bledsoe