When DNS Broke Our Azure App — and Everything Looked Healthy
This one was sneaky.
Azure App Gateway — healthy
App Service — running
AFD probes — green
Logs — clean
But users were timing out. Pages were loading slow. Something was off.
The Issue with ?
Private DNS Zone wasn’t linked to the right VNet.
Our backend API (moved behind a Private Endpoint) couldn’t resolve the FQDN.
No error — just quiet timeouts.
Fix Applied:
Linked the right Private DNS Zone to staging VNet
Cleared stale records
Restarted the App Service to reset DNS cache
Learnings:
In Azure, DNS issues don’t always throw errors — sometimes they just break user experience silently.
Always double-check:
DNS zone links
NSG + UDR routing
App-level DNS caching
Have you been bitten by DNS in the cloud? Let’s share battle scars
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