Field Notes — Weekly
Things we learned the hard way, written down.
Engineering notes from real environments — the failure signatures, root causes, and fixes we wish someone had published before we needed them. New notes weekly.
VTS-FN-001 · July 7, 2026
Exchange 2019 and Windows Server 2025 domain controllers: the version trap that takes down mail flow
Why a routine DC refresh can break Active Directory topology discovery, the CU-gated supportability matrix nobody reads, and the fastest way out of the outage.
Read the note → VTS-FN-002 · July 15, 2026Deploying Claude for your business: identity, isolation, and cost control
The architecture decisions that separate an enterprise AI assistant from a liability — server-injected identity, per-user session ownership, and cost control as a security discipline.
Read the note → VTS-FN-003 · July 22, 2026Your backups aren't tested until you've restored them
Why verification and scheduled restore tests are different disciplines, and the quiet failure modes only the second one catches.
Read the note →