At http://localhost:50070/dfsnodelist.jsp?whatNodes=LIVE, there is a list of Live datanodes in a table. In the Node column, there is a link to each node. If you hover your cursor over one of the links, it shows the IP address and port number of the datanode. However, actual link is the hostname instead of the IP.
Suggest that the tooltip reflect the actual url that the web browser would go to if the link is selected.