Unix and Linux clients cannot download the inventory package from a package server. They are communicating with the NS server and sending basic inventory.

If you check the inventory package, there will be a .aex-pkg-codebases-\{B89D89CA-DF94-4FC6-8DE4-D2EB4BB50984\} file. This file is downloaded from the NS server. If it exists, then the client is communicating with the NS server. This file contains the names of the package server(s) from which the client should download the inventory package as defined by the NS package server and site maintenance settings. It is this package server hostname that the client cannot resolve.

There should also be a .aex-pkg-snapshot-\{B89D89CA-DF94-4FC6-8DE4-D2EB4BB50984\}file. However, in this case, it is being downloaded from the package server but the client cannot resolve the package server hostname.  Because of this, the download of the snapshot and the inventory package fails.