You work for a large software company in Seattle. They have their production environment provisioned on AWS inside a custom VPC. The VPC contains both a public and private subnet. The company tests their applications on custom EC2 instances inside a private subnet. There are approximately 500 instances, and they communicate to the outside world via a proxy server. At 3am every night, the EC2 instances pull down OS updates, which are usually 150MB or so. They then apply these updates and reboot: if the software has not downloaded within half an hour, then the update will attempt to download the following day. You notice that a number of EC2 instances are continually failing to download the updates in the allotted time. Which of the following answers might explain this failure? [Select 2]