In the following HA+Federated setup with two nameservices ns1 and ns2:
- ns1 -> namenodes nn1, nn2
- ns2 -> namenodes nn3, nn4
- fs.defaultFS is hdfs://ns1.
A webhdfs request issued to nn3/nn4 will be routed to ns1. This is because setClientNamenodeAddress initializes NameNode#clientNamenodeAddress using fs.defaultFS before the config is overriden.