Finding out what's been registered as a trademark in Cambodia is possible through a handful of ways, the following is a quick round-up.
Official Search by the Department of Intellectual Property
The only way to obtain an official statement of what marks have been registered and pending is to request the DIP to perform a search. Unlike the services listed below, the DIP will report any marks that it considers similar to the one searched for. Anyone, or their licensed trademark agent, may request a search by submitting the appropriate form in person and paying the official fee of US$10 fee per search.
Online Search on Department of Intellectual Property's Website
The DIP has recently made its database of registered marks available for free online. The search function is quite basic, with fields only for mark name and mark owner. The site's disclaimers note that the search results only show identical marks or marks containing exactly the term in the search field. In other words, the results do not show merely similar marks. Further, the search only covers registered marks, not those pending. The search result will show the applicant name, address and number, date, a sample of the mark, and the Nice classification (though this is often missing).
World Intellectual Property Organization - Global Brands Database
WIPO's database covers both registered and pending marks, and allows the user to search by name, brand, mark, class, and application date., etc.
A recent check showed the lag-time between filing and appearing as pending in this database is only a few days.
ASEAN Trademark View
ASEAN Trademark View was developed by the IP offices of ASEAN member states, with the support of the European Union. The website allows one to simultaneously search all ten countries' databases for both registered and pending marks. The advanced search function has the full set of fields you'd expect, and the results contain even more information than the WIPO database - including Vienna classification codes, opposition and cancellation proceedings, and renewal information. It even allows one to automatically translate information into other South-East Asian languages.