What is the cause of this issue?

Refer to the exhibit.

An engineer troubleshoots connectivity issues with an application. Testing is performed from the server gateway, and traffic with the DF bit set is dropped along the path after increasing packet size. Removing the DF bit setting at the gateway prevents the packets from being dropped .

What is the cause of this issue?
A . PMTUD does not work due to ICMP Packet Too Big messages being dropped by an ACL
B . The remote router drops the traffic due to high CPU load
C . The server should not set the DF bit in any type of traffic that is sent toward the network
D . There is a CoPP policy in place protecting the WAN router CPU from this type of traffic

Answer: C