Selected Answer: BC The Cisco SD-WAN TCP Optimization feature locally terminates TCP connections at the WAN edge routers and uses TCP Selective Acknowledgment (SACK) to better control the TCP-Window-Size and maximize throughput through the WAN links.

Selected Answer: CD The optimization is performed between both end routers: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/optimization-ha/ios-xe-16/network-optimization-high-availability-book-xe/m-tcp-optimization.html#:~:text=This%20feature%20optimizes%20TCP%20data,trip%20latency%20and%20improve%20throughput.

It is recommended that you configure TCP optimization on both routers, the router closer to the client and the router closer to the server. This setup is sometimes called a dual-ended proxy. "It is possible to configure TCP optimization only on the router closer to the client", a case called single-ended proxy, but this setup is not recommended because the TCP optimization process is compromised. TCP is a bidirectional protocol and works only when connection-initiation messages (SYNs) are acknowledged by ACK messages in a timely manner. I dont know... it could be local (at client) and it uses Selective ACK...

When you enable TCP optimization on the two routers, Router A terminates the TCP connection from the client and establishes a TCP connection with Router B. Router B then establishes a TCP connection to the server. The two routers cache the TCP traffic in their buffers to make sure the traffic from the client reaches the server without letting the TCP connection time out. Not mentioning termination of remote TCP connection here , so why D is correct?

A and C could be right : https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/appqoe/ios-xe-17/appqoe-book-xe/m-tcp-optimization.html#:~:text=TCP%20optimization%20fine%20tunes%20the,Catalyst%20SD%2DWAN%20devices.

It is B and C. When you turn on TCP optimization on the two routers, Router A terminates the TCP connection from the client and establishes a TCP connection with Router B.

Selected Answer: BC From this article: https://www.networkacademy.io/ccie-enterprise/sdwan/application-quality-of-experience-appqoe#:~:text=The%20Cisco%20SD%2DWAN%20TCP,throughput%20through%20the%20WAN%20links.

Selected Answer: BC BC The Cisco SD-WAN TCP Optimization feature locally terminates TCP connections at the WAN edge routers and uses TCP Selective Acknowledgment (SACK) to better control the TCP-Window-Size and maximize throughput through the WAN links

IMHO the SACK feature in TCP has been standard for years between ordinary TCP hosts. I don't quite get why Cisco SD-WAN is calling this groundbreaking SD-WAN optimization.