I'm not sure, but I believe it uses the name the DN used to register with the NN. But… The NN will reject registrations from unresolvable hostnames so I believe DNS is mandatory.
On Mar 11, 2013, at 12:58 PM, Steven Matthews wrote:
> I'm writing some test code to try out the WebHDFS REST API for potentially adding functionality to a program. If I want to create and write to a file using the API, I would send the initial create request and I would get back a location of a datanode as the documentation says I should. The location I'm getting back however is a name and not an IP. Now if had this name registered in my DNS server or put in an entry in my hosts file then I can successfully make the 2nd create call using that name and I would have just created a file. Is there any reason why it doesn't respond with an IP address? Is this something that it could be configured to do? In a fully-distributed Hadoop setup this would seem like a big pain to register and maintain all the datanode names and their IPs for machines across the internet just so I can resolve a name.