Hi Prashant,
Yes, one DDoS Network Protection Plan covers multiple different regions. If you have less than 100 Public IP addresses then it would be $2,944/month to cover all of them.
Excerpt from documentation:
Although DDoS Protection Plan resources needs to be associated with a region, users can enable DDoS protection on Virtual Networks in different regions and across multiple subscriptions under a single Microsoft Entra tenant.
Please also see pricing examples at bottom of pricing page:
Azure DDoS Protection pricing
https://azure.microsoft.com/en-us/pricing/details/ddos-protection/
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Thanks.
-TP