1. A method, comprising: validating a lookup operation by: accessing, by a processor, a distributed balanced tree having a plurality of nodes distributed across a plurality of servers; retrieving, by the processor, version information associated with a node of the distributed balanced tree; and determining, by the processor, in a single round trip to the servers, validity of the lookup operation performed on the distributed balanced tree based on a version value of only the leaf node accessed during the lookup operation and the retrieved version information; and validating a transaction that modifies a node by: retrieving, by the processor, a version value of each of the nodes modified by the transaction on each of the servers independently of each other of the servers; comparing each retrieved version value with a version value acquired while traversing the distributed balanced tree for the transaction; and determining, based on results of the comparison, whether the transaction is successful; wherein each of the nodes to be validated is locked only while the corresponding server copies the node for retrieval by the processor.