The hosts.lpd file provides:

A.
A list of network printer IP addresses.

B.
A list of printers available on the local network.

C.
A list of computers that have printer (lpd) daemons running.

D.
A list of hosts allowed to use printers on the local machine.

E.
A list of hosts on the local network that are not allowed access to printers attached to the local machine.

Explanation/Reference:
From http://www.regatta.cmc.msu.ru/doc/usr/share/man/info/ru_RU/a_doc_lib/files/aixfiles/hosts.lpd.htm:
The /etc/hosts.lpd file defines which remote systems are permitted to print on the local system.