yppoll —
ask version of NIS map from NIS server
  
    | yppoll | [ -T] [-hhost] [-ddomain] mapname | 
yppoll asks a NIS server process for the order number
  and which host is the master server for mapname.
The options are as follows:
  - -T
- Use TCP protocol instead of UDP for request if the
      -hoption is present.
- -hhost
- Ask the NIS server process running on host for
      information about mapname. If
      host is not specified, the server polled is the
      default server returned by
      ypwhich(1).
- -ddomain
- Use the NIS domain domain instead of the default
      domain as returned by
      domainname(1).
Theo de Raadt and John Brezak