I've got a server that is available only via ipv6.
The mongo-shell works perfect for me with adding --ipv6 parameter, but mongodump command doesn't accept it (the 2.6 version did):

$ mongodump --ipv6 -h ipv6.server.com:27017
2016-01-29T16:28:53.055+0500    error parsing command line options: unknown option "ipv6"
2016-01-29T16:28:53.056+0500    try 'mongodump --help' for more information

Documentation says it should.

As a workaround [ipv6:address:notation]:27017 works for me now, but it's less convenient than it used to be.