Hi @Sibi Chakaravarthi Murugesan ,
Thanks for reaching out to Microsoft QnA.
N series VMs are not available in all regions. You could check the region wise availability here and try deploying the VM to some other region where the VM size is available. Please check the below images for reference.
You will not be able to deploy a N series VM to a region where it is not available. You can only deploy a N series VM to a region where it is available, however, the vCPU quota might be insufficient at times as mentioned here - sizes-gpu, but you can open a support request with Azure support and they shall increase the limit for your subscription.
Please feel free to reach out to us incase of any queries. I hope this helps.
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