On‑premises DNS → Azure DNS Migration Tool Estimator Checklist

August 25, 2025124 views0

Move your authoritative DNS from on‑premises Linux/BIND (or similar) to Azure DNS with confidence. This tool provides a prescriptive path end‑to‑end: a step‑by‑step runbook, interactive checklists, and a per‑zone tracker to plan, stage, cut over, validate, and decommission at scale. You’ll also find DNSSEC guidance, apex/alias tips for edge services, validation commands, and a tested rollback plan—so you can run controlled change windows in batches and keep clean audit evidence. On‑premises DNS → Azure DNS Migration Tool

On‑premises DNS → Azure DNS Migration Tool

Use this interactive checklist to migrate authoritative DNS zones from on‑premises Linux/BIND to Azure DNS. Replace placeholders like example.com with your actual values.

Overall Progress 0%

Import State

0) Prerequisites & Governance

Azure subscription, resource group(s) created (e.g., rg-dns). Azure CLI installed and authenticated (az login). Registrar access confirmed for each domain. RBAC: Assign DNS Zone Contributor at zone/RG scope for DNS admins. Security: Enforce MFA/strong auth on management plane. Rollback: Ability to restore legacy registrar NS quickly is documented.

1) Current State & Delegation Snapshot

Enumerate all zones and their authoritative NS at registrar. Identify in‑bailiwick NS needing glue records (e.g., ns1.legacy.example.com). Baseline SOA/NS/record counts for each zone. Flag special records: SPF/TXT, DKIM/DMARC, SRV, CAA, wildcards, apex targets.

Helpful Commands

dig NS example.com +short
dig A ns1.legacy.example.com +short
dig SOA example.com +noall +answer

2) Design Decisions

Public authoritative zones → Azure DNS (public). Internal resolution? Use Azure Private DNS + Azure DNS Private Resolver. Adopt DNSSEC for public zones (Yes/No decision recorded). Edge/perf/security: Front Door (Std/Premium), or Traffic Manager for routing. Apex strategy: Alias A/AAAA → Front Door / Traffic Manager / Public IP.

3) Pre‑Cutover (T‑7 → T‑1)

Lower TTLs to 300s for SOA minimum and key records on legacy DNS. Export zone files from legacy (BIND dump or AXFR from secondary). Create Azure DNS zones with correct RG/tags/naming. Import zone files to Azure; reconcile record counts/types vs baseline. Normalize: SPF as TXT, split long TXT, verify SRV, CAA, DMARC/DKIM. Configure diagnostics/metrics (cost‑aware categories). Finalize rollback plan and communication channels.

Azure CLI Examples

az group create -n rg-dns -l australiaeast
az network dns zone create -g rg-dns -n example.com
az network dns zone import -g rg-dns -n example.com -f ./example.com.zone

4) Cutover (T0)

Freeze legacy changes; archive final zone exports. Update registrar NS to the 4 Azure nameservers assigned to the zone. (If DNSSEC) Publish DS at registrar per sequence decision. Validate immediately: dig NS, dig SOA, dig +trace, and if DNSSEC: delv. Application smoke tests (top URLs, API endpoints, MX delivery, SRV services).

Validation Snippets

dig NS example.com +short
dig SOA example.com @1.1.1.1 +short
dig +trace example.com
# DNSSEC
delv example.com

5) Post‑Cutover Stabilization (T+0 → T+2 days)

Monitor Azure DNS metrics (QueryVolume, RecordSetCount/capacity). Keep legacy servers online in read‑only mode (~48 hours). Raise TTLs back to normal after stability proven. Enable focused diagnostic logs/retention (cost‑aware).

Rollback Plan (Keep handy during T0)

When to trigger

Critical availability or security issue immediately after NS switch.
Widespread NXDOMAIN/invalid answers not fixable within the window.
DNSSEC validation failures at scale.

Actions

At registrar, restore legacy NS set.
Keep/force TTL at 300s to accelerate cache turnover.
Diff Azure vs legacy zone files; correct record mismatches.
Re‑run shadow validation; schedule a fresh cutover window.

Per‑Zone Tracker

Track each zone through the migration stages. Data is saved locally in your browser.

Zone Name

Notes (optional)

Import CSV

Zone	TTL↓	Export	Import	Counts	Shadow	NS→Azure	Validate	TTL↑	Notes	Delete

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