In IPv6 what is the major difference concerning application layer vulnerabilities compared to IPv4? 

Implementing IPv4 security in a dual-stack network offers protection from IPv6 attacks too. 

Vulnerabilities in the application layer are independent of the network layer. Attacks and mitigation techniques are almost identical. 

Due to the extensive security measures built in IPv6, application layer vulnerabilities need not be addresses. 

Vulnerabilities in the application layer are greatly different from IPv4.