This BAOI guide provides a structured method for testing ipv6 without breaking ipv4 without multiplying unnecessary changes.
Avant de commencer : adaptez toujours les commandes et manipulations à votre environnement. Sur un système de production, prévoyez une backup ou un retour arrière lorsque l’action peut modifier la configuration.
Étapes à suivre
1
Set perimeter
Identify the equipment, service, affected users and start time.
2
Collect Elements
Record the exact messages, logs and useful settings.
3
Test methodically
Start with the basic dependencies before the application components.
4
Apply correction
Change only the identified parameter or component.
5
Validate
Rewrite the full scenario and document the result.
Commands utiles
ipconfig /all.
ping -6 instance.com
À retenir
Keep the initial values for a backwards.
Avoid multiple simultaneous changes.
Compare with a functional configuration when possible.
Technical deep dive
IPv6 in dual stack: test without breaking the IPv4 path
Technical checkpoints
A host can receive IPv6 via RA/SLAAC, DHCPv6 or both depending on the network; the default gateway typically comes from Router Advertisements.
An AAAA record can make clients prefer IPv6; partially working IPv6 can cause delays before IPv4 fallback.
Testing -4 and -6 separately allows comparison without disabling either stack.
Globally disabling IPv6 to hide an AAAA/RA issue can break services that depend on it.
A link-local fe80:: address is locally necessary but does not prove routed IPv6 connectivity.
How to validate
Global/ULA address, default route and AAAA DNS are coherent.
The same service works over -4 and -6 according to the intended design.
Operational context
IPv6 validation should prove dual-stack behavior without assuming IPv4 will continue to mask broken IPv6. Test addressing, router advertisements, DNS, routing, path MTU and application reachability separately so a partial IPv6 deployment does not create slow fallbacks or intermittent access.
Step-by-step checks
Confirm the client has the expected IPv4 and IPv6 addresses, prefix length, default gateways and DNS servers; identify temporary, link-local and global IPv6 addresses correctly.
Resolve the same service through A and AAAA records and verify that the returned IPv6 destination is intentional before testing application traffic.
Test IPv6 gateway and remote reachability independently from IPv4, then compare route selection and latency rather than disabling one protocol to make the symptom disappear.
Validate ICMPv6 and path-MTU behavior across firewalls and VPNs because blocking essential ICMPv6 messages can break an otherwise correct dual-stack path.
Useful verification commands
Use commands only on systems you administer and capture the read-only output before making a configuration change.
ipconfig /all
route print -6
Resolve-DnsName example.com -Type AAAA
ping -6 example.com
How to validate the result
A dual-stack client must reach the intended services over IPv6 when AAAA records are present, keep normal IPv4 reachability, and show no abnormal fallback delay when either protocol is selected.
Evidence to keep
Keep interface addresses, default routes, DNS A/AAAA answers, IPv4/IPv6 reachability results, path-MTU observations and the tested application URL or endpoint.
Frequently asked question
Should I disable IPv6 to prove it is the problem?
Not as a first diagnostic step. Disabling IPv6 changes the selection logic and can hide the real DNS, routing, firewall or MTU fault. Compare IPv4 and IPv6 paths first.