If you've come across zfeed-video-mcloud-lpl-s12-te-vnso-pt-47.zadn.vn in your network logs or browser, you're likely dealing with a content delivery node. This subdomain is part of zadn.vn, which belongs to FPT Telecom, a major Vietnamese internet provider. It's built to serve video or other large files quickly, not to host a business website.
For that reason, many of the usual trust checks — like an about page, contact info, or legal policies — don't apply here. The subdomain has a valid SSL certificate and uses modern encryption, though it also supports older TLS versions as a fallback. That's a minor concern for a CDN node, but not a dealbreaker.
There's no web archive history, so the subdomain may be relatively new or just not indexed. It's not on any blacklists and hasn't been flagged by Google. If you're worried about safety, the bigger question is whether the main domain (zadn.vn) is trustworthy — and that's a separate check. For this subdomain alone, there's no evidence of anything malicious. It's best to treat it as what it appears to be: a technical component of a larger network.