Amazon VPC lets you create a virtual network in the cloud that you control–subnets, ip ranges, internet access, routing, etc. At recent classes, I was asked some questions about VPC that I dug into to find answers.
- Does AWS VPC support multicast or broadcast?
- No, per the FAQs. But there are some projects to overlay multicast functionality on top of the unicast network within a VPC.
- Are vpc flow logs add on pricing?
- There is no additional charge, but they go into Cloudwatch Logs and you are charged at the normal rate for that usage.
- Is the NAT Gateway (used to provide internet access to ipv4 private subnets) highly available?
- It is redundant within an availability zone. But, from the docs: “If you have resources in multiple Availability Zones and they share one NAT gateway, in the event that the NAT gateway’s Availability Zone is down, resources in the other Availability Zones lose Internet access. To create an Availability Zone-independent architecture, create a NAT gateway in each Availability Zone and configure your routing to ensure that resources use the NAT gateway in the same Availability Zone.” See also the Egress-only Internet Gateway, if you are using ipv6.