Trusting DSCP is essential for maintaining the QoS markings across the wired and wireless network in a FlexConnect deployment. By trusting DSCP, the WLC and APs will preserve the QoS markings set by applications and devices, ensuring consistent QoS treatment throughout the network. References := (CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide)

If PEAP authentication is failing and the server is sending an Access-Reject message, one possible action to resolve the issue is to disable the server certificate validation on the client. This means that the client device will not check the authenticity of the RADIUS server's certificate, which can sometimes resolve connection issues, especially if there is a problem with the certificate chain or trust settings. However, this should be done with caution as it reduces the security of the authentication process. References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide

TACACS+ (Terminal Access Controller Access-Control System Plus) is recommended for managing device access as it provides a more granular level of control over user authentication and authorization than RADIUS. It allows for different levels of access based on user identity by interfacing with external repositories such as Active Directory or LDAP. This protocol helps in distinguishing between different users and assigning appropriate access rights based on their roles within an organization. References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide