The bucket payload contains 2 lists of nodes:
- the nodes list
- the nodesExt list
The nodes contains the nodes on which this bucket is deployed. It is the case that there will be a time lag between when the node shows up in the nodes list and when the bucket is created on the node in question, but it eventually will be there. For couchbase buckets, it will be some further time before a vbucket is created on this node - and obviously for this refer to the vbucket map.
The nodesExt is a global list (i.e. not specific to the bucket) of all active nodes in the cluster. This list contains information about the node such as hostname and the services that are running on this node along with the associated ports. There may be more nodes in the nodesExt list than are in the nodes list (e.g. N1QL or 2i only nodes will show in the nodesExt list but not in the nodes list.)
In the case of memcached buckets assuming that the bucket is present on all nodes can lead to problems during transitions such as delta node recovery situations where the bucket is not yet on the node.