Issue reported by user but reproducible by me.

When working with the 2.4 Java driver on Mac OS X (10.6.x) , where mongod listens on bind_ip 127.0.0.1 (also tried with 'localhost'), an empty Mongo constructor [Mongo()] connects. However, connecting to a hostname of "localhost" fails with:

com.mongodb.MongoInternalException: DBPort.findOne failed
at com.mongodb.DBPort.findOne(DBPort.java:153)
at com.mongodb.DBPort.runCommand(DBPort.java:159)
at com.mongodb.DBTCPConnector.testMaster(DBTCPConnector.java:371)
at com.mongodb.Mongo.<init>(Mongo.java:167)
at com.mongodb.Mongo.<init>(Mongo.java:151)
at com.mongodb.Mongo.<init>(Mongo.java:119)

Adding an explicit port number makes no difference.'

User reports they see same behavior if they specify a hostname of "127.0.0.1" although on my machine with a homebrew sourced 1.6.3 and 1.6.5 it functions with "127.0.0.1". If I remove the bind_ip declaration it works fine.

User reports behavior did not occur with the 2.1 Java driver — I've confirmed this. Uncertain if it happens on other platforms yet.