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ANS-C01 · Question #256

A company is running its application servers on Amazon EC2 instances. The EC2 instances run in separate VPCs that are connected by a transit gateway. The EC2 instances launch in a private subnet…

The correct answer is D. Instruct the application team to set the maximum transmission unit (MTU) of the system's network. To increase the payload size per packet between EC2 instances communicating through a Transit Gateway, the network engineer should instruct the application team to set the MTU of the EC2 instances' network interfaces to 8500.

Submitted by andreas_gr· Mar 6, 2026Network Implementation

Question

A company is running its application servers on Amazon EC2 instances. The EC2 instances run in separate VPCs that are connected by a transit gateway. The EC2 instances launch in a private subnet with a route to the transit gateway for internal and external connectivity. The external connectivity is provided by a VPC with firewall devices that perform an inspection for packets that ingress and egress through an internet gateway. A network engineer needs to help the company's application team increase the payload size per packet delivery between the EC2 instances. All network connectivity must be through the transit gateway What should the network engineer do to meet these requirements?

Options

  • AEnable jumbo frames on the transit gateway. Instruct the application team to set the maximum
  • BInstruct the application team to set the maximum transmission unit (MTU) of the VPC to 8500
  • CInstruct the application team to set up enhanced networking on the system by using the enhanced
  • DInstruct the application team to set the maximum transmission unit (MTU) of the system's network

How the community answered

(28 responses)
  • A
    14% (4)
  • B
    4% (1)
  • C
    7% (2)
  • D
    75% (21)

Why each option

To increase the payload size per packet between EC2 instances communicating through a Transit Gateway, the network engineer should instruct the application team to set the MTU of the EC2 instances' network interfaces to 8500.

AEnable jumbo frames on the transit gateway. Instruct the application team to set the maximum

While enabling jumbo frames (higher MTU) on the Transit Gateway is part of the solution (it's implicitly 8500 by default for VPC attachments), instructing the application team to set the MTU to *9001* is incorrect as the Transit Gateway supports 8500, not 9001, for VPC attachments.

BInstruct the application team to set the maximum transmission unit (MTU) of the VPC to 8500

Setting the MTU 'of the VPC' is not a direct configuration; MTU is configured at the instance network interface level or implicitly by the service, making this option technically inaccurate regarding where MTU is set.

CInstruct the application team to set up enhanced networking on the system by using the enhanced

Setting up enhanced networking (like ENA) improves network performance, throughput, and packet per second (PPS) rates, but it does not directly increase the maximum payload size per packet (MTU).

DInstruct the application team to set the maximum transmission unit (MTU) of the system's networkCorrect

AWS Transit Gateway supports an MTU of 8500 bytes for traffic between attached VPCs. For EC2 instances to effectively utilize this larger MTU and increase payload size per packet, their operating system network interface MTU must also be configured to 8500, aligning with the Transit Gateway's capabilities.

Concept tested: MTU Configuration with Transit Gateway

Source: https://docs.aws.amazon.com/vpc/latest/tgw/transit-gateway-mtu.html

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