Final answer:
For optimal security alongside Virtual Network Peering, Network Security Groups (NSGs) offer a way to filter traffic to and from Azure resources, and Azure Firewall or a third-party firewall appliance can be used to provide a complete network-level security solution.
Step-by-step explanation:
When utilizing Virtual Network Peering, which allows seamless connectivity between two or more virtual networks in Azure or other cloud services, it's highly recommended to implement Network Security Groups (NSGs) alongside it for optimal security. NSGs provide an additional layer of security by allowing you to filter network traffic to and from Azure resources in an Azure virtual network. An NSG contains security rules that allow or deny inbound network traffic to, or outbound network traffic from, several types of Azure resources. To strengthen the security stance further, implementing Azure Firewall or a third-party firewall appliance, in conjunction with NSGs, would deliver comprehensive network-level security, including threat intelligence, malware protection, and application rule collection features.