Hi @sandeep ,
you don't see the VM sizes of the N-Series at all?
It could be N-Series isn't available in the selected Azure region.
If the VM Size is available in the selected Azure region you will see the VM size ... no matter if the vCPU quota is insufficient or sufficient.
If the N-Series VM SKU isn't available in the selected Azure Region the Azure support could not help. Your only option is to select an Azure region that offers the N-Series VMs.
If the N-Series is available in the Azure Region but you vCPU quota is insufficient you could reach out to the Azure support to increase the limit.
Azure Portal
-> Subscription
-> Usage + quotas
-> Request Increase
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten