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Best Practice for Managing Common Blocked IPs Across Multiple Azure Firewalls, Regions, and Subscriptions

$@chin 375 Reputation points
2026-05-12T05:06:54.15+00:00

Multiple Azure Firewalls deployed across different regions and subscriptions, and in order to block a common set of IP addresses across all environments.

Currently, i'm evaluating the best design approach for managing these shared blocked IPs centrally instead of maintaining them individually in each Firewall Policy.

Which approach would be considered best practice from a scalability, manageability, and performance perspective?

Option 1:

  • Use a single centralized IP Group shared across all Azure Firewalls across regions and subscriptions.

Option 2:

  • Use separate IP Groups per region, but shared across firewalls different subscription

Are there any limitations or recommendations from Microsoft regarding cross-region or cross-subscription IP Group usage with Azure Firewall Policies ?

Azure Firewall
Azure Firewall

An Azure network security service that is used to protect Azure Virtual Network resources.

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  1. Venkatesan S 9,565 Reputation points Microsoft External Staff Moderator
    2026-05-12T05:44:41.92+00:00

    Hi $@chin,

    Thanks for reaching out in Microsoft Q&A forum,

    Which approach would be considered best practice from a scalability, manageability, and performance perspective? Option 1:

    • Use a single centralized IP Group shared across all Azure Firewalls across regions and subscriptions. Option 2:
    • Use separate IP Groups per region, but shared across firewalls different subscription

    For managing shared blocked IP addresses across multiple Azure Firewalls in different regions and subscriptions, a single centralized IP Group (Option 1) stands out as the clear winner for scalability and manageability. You update one resource, and the changes instantly apply everywhere no more chasing duplicates across environments. Performance stays solid too, since IP Groups are built for this kind of reuse without introducing latency or overhead.

    Option 2, with separate IP Groups per region, adds unnecessary complexity: you'd juggle multiple groups for the same IPs, risking inconsistencies during updates. A centralized approach keeps things lean, especially as your footprint grows.

    A single IP Group provides true central control one change scales globally across subscriptions and regions while per-region groups (Option 2) demand more effort to maintain alignment and increase administrative overhead without performance gains.

    Are there any limitations or recommendations from Microsoft regarding cross-region or cross-subscription IP Group usage with Azure Firewall Policies?

    Limitations and Microsoft Guidance

    IP Groups are regional by nature but globally referenceable, even across subscriptions—Microsoft confirms they're mirrored to paired regions for resilience, so a single-region outage won't break cross-region firewalls. No hard cross-subscription blocks exist, though group names must be unique per subscription. Limits cap at around 200 groups per policy (check quotas), and parallel updates handle bulk changes efficiently.

    Pair this with Azure Firewall Manager for policy-level centralization across subscriptions—it's the pro move for enterprise-scale governance.

    Update:

    In the event of a regional outage affecting Region A, will the firewalls in Regions B and C also be impacted due to their dependency on the shared IP Group ?

    No, firewalls in Regions B and C will not be impacted by a regional outage in Region A. Azure IP Groups are designed with high availability: when created in one region, they are automatically mirrored to a paired region via the resource provider, ensuring the configuration remains accessible globally.

    Microsoft confirms IP Groups are global and usable across regions regardless of storage location the Azure Portal explicitly states this during creation. In a Region A outage, firewalls in B and C reference the mirrored copy from the paired region, keeping rules enforced without disruption.

    Updates or management might be temporarily unavailable from Region A during outage, but runtime enforcement continues unaffected (very low risk, as validated by product team).

    Official Microsoft Documentation:

    Kindly let us know if the above helps or you need further assistance on this issue.

    Please do not forget to 210246-screenshot-2021-12-10-121802.pngand “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

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  2. AI answer

    2026-05-12T05:07:08.18+00:00

    For centralized management of a common blocked IP list across multiple Azure Firewalls, regions, and subscriptions, the recommended pattern is to standardize on shared IP Groups and Firewall Policies rather than duplicating per-region objects.

    From a scalability, manageability, and performance perspective:

    1. IP Groups are explicitly designed to be reusable across:
      • Multiple Azure Firewalls
      • Multiple regions
      • Multiple subscriptions
      This is supported both for Azure Firewall and Azure Firewall policy:
      • “You can use IP Groups in Azure Firewall DNAT, network, and application rules for multiple firewalls across regions and subscriptions in Azure.”
      • “IP Groups can be reused in Azure Firewall DNAT, network, and application rules for multiple firewalls across regions and subscriptions in Azure.”
    2. Best-practice guidance for network security and Azure Firewall emphasizes:
      • Standardizing on IP Groups instead of raw IPs for central management.
      • Using Firewall Manager and Firewall Policy objects to manage rules centrally.
      • Using IP Groups to reduce rule count and stay within Azure Firewall limits.

    Given this, the preferred design is logically equivalent to Option 1:

    • Maintain a central set of IP Groups (for example, one or a small number of “global blocklist” IP Groups) and reference them from a global Azure Firewall policy that is associated with all Azure Firewalls across regions and subscriptions.
    • This gives a single point of change for the blocked IP list and leverages the built-in cross-region/cross-subscription reuse capability of IP Groups.

    Using separate IP Groups per region (Option 2) is technically supported but adds management overhead and increases the risk of drift without providing performance benefits, because Azure already supports sharing IP Groups across regions and subscriptions.

    Microsoft guidance and limitations relevant to cross-region/cross-subscription use:

    • IP Groups:
      • Are supported as source/destination in DNAT, network, and application rules.
      • Can be reused across multiple firewalls across regions and subscriptions.
      • Require unique group names.
    • Architecture and security guidance recommends:
      • Creating a global Azure Firewall policy to govern security posture across the global network environment and assigning it to all Azure Firewall instances.
      • Standardizing on IP Groups and Service Tags instead of raw IPs for centralized management.
      • Using IP Groups to reduce the number of individual IP rules and help stay within Azure Firewall limits.

    No additional performance penalties or specific limitations are documented for using IP Groups cross-region or cross-subscription beyond the need for unique names and normal policy association behavior.

    In practice, the recommended pattern is:

    1. Define one or more global “blocked IP” IP Groups at the policy level.
    2. Use these IP Groups in a global Azure Firewall policy (managed via Azure Firewall Manager) for DNAT/network/application rules.
    3. Associate that policy with all Azure Firewalls in all regions/subscriptions.

    This achieves centralized, scalable, and consistent management of blocked IPs with minimal duplication.

    References:

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