Zero trust is easy to endorse and hard to run. This post focuses on the practical, hands-on reasons zero trust network access implementations break in production — the issues security and network teams actually hit when they move from architecture diagram to live enforcement — backed by data from Gartner, the Cloud Security Alliance, NIST, and field research from ZTNA and microsegmentation vendors. If you’re still getting oriented on the fundamentals of ZTNA , start there and come back for the deployment specifics below.