Exam 300-420 topic 1 question 97 discussion

C) is the correct answer. Traffic Symmetry for Application Visibility For the localized application visibility features (DPI and NBAR2) to be able to classify most application traffic, it is important that the WAN Edge router sees network traffic in both directions. In dual-WAN Edge sites without any policy enabled, equal cost paths exist over each transport and to each WAN Edge router, and network traffic is hashed depending on fields in the IP header. Traffic is unlikely to always be forwarded to the same WAN Edge router in both the LAN-to-WAN direction and the WAN-to-LAN direction. To maintain symmetric traffic, it is recommended to set up routing so that traffic prefers one WAN Edge over another at dual-WAN Edge router sites.

Traffic Symmetry for Application Visibility, C is correct

Correct C

C. Traffic must be symmetrical as it egresses the WAN Edges and returns from remote sites for DPI to function properly. When dual WAN Edge routers are deployed at a branch site, one of the design considerations is to ensure that traffic is symmetrical as it egresses the WAN Edges and returns from remote sites. This symmetry is crucial for proper functioning of Deep Packet Inspection (DPI) and other security features that require consistent traffic flows. Asymmetric traffic flows can lead to incorrect DPI results, ineffective security policies, and overall degraded network performance. To achieve symmetrical traffic flows, it's essential to carefully plan routing policies and load balancing mechanisms in the SD-WAN design.

Answer C

See: https://www.cisco.com/c/en/us/td/docs/solutions/Verticals/EE/IG-WAN/EE-WAN-IG/EE-WAN-IGch1.html

Correct Answer is C

Answer A is incorrect. AS-path prepending influences ingress traffic - not egress traffic as stated in the answer A

Answer is A is correct as is.