You can specify an NTP server via DHCP, or Group Policy, or DNS SRV records.

DHCP:

dhcp

GPO:

gpo

SRV Record:

srv record

If your client is unable to leverage any of those mechanisms... you can also pretty safely assume that all Active Directory domain controllers are also NTP servers. Which means that you should be able to find one simply by resolving the name of the domain itself, e.g. company.com or ad.company.com and you'll likely hit an NTP server, without the need to specify individual hostnames.