Refer to the exhibit.

Which statement is true about where trust boundaries should be established in a network?

A.
Endpoints 2 and 3 are optimal places to establish a trust boundary. Endpoint 1 is an
acceptable place to establish a trust boundary.

B.
Endpoint 2 is the optimal place to establish a trust boundary. Endpoints 1 and 3 are
acceptable places to establish a trust boundary.

C.
Endpoint 2 is the only acceptable place to establish a trust boundary.

D.
Endpoint 1 is the only acceptable place to establish a trust boundary.

E.
Endpoints 1 and 2 are optimal places to establish a trust boundary. Endpoint 3 is an
acceptable place to establish a trust boundary.

F.
Endpoint 1 is the optimal place to establish a trust boundary. Endpoints 2 and 3 are
acceptable places to establish a trust boundary.

Explanation:
Trust Boundaries:
When connected by a single cable, the IP phone is the edge of the managed network. An
integral part of the Cisco network design architecture has always been the classification, or
coloring, of traffic as close to the edge of the network as possible. As such, the IP phone can
and should classify traffic flows.
Try to maintain the trust boundary in the wiring closet. If necessary, move it down to the
distribution layer on a case-by-case basis, but avoid moving it to the core of the network.
This advice conforms to the general guidelines for keeping the trust boundary as close to the
source as possible.
By default, Cisco IP phones mark all VoIP traffic with CoS=5 and DSCP=46. However, it is
critical to make sure that the PC connected to the access port of the IP phone is not also
classifying traffic. The recommended method for ensuring this is to extend the trust boundary
of the Ethernet switch to the IP phone and not beyond, meaning the IP phone will re-classify
all traffic coming from the PC with CoS=0.
References:
www.cisco.com/en/US/products/sw/cscowork/ps2064/products_user_guide_chapter09186a0
08007ff73.html
www.cisco.com/en/US/products/hw/video/ps1870/products_implementation_design_guide_c
hapter09186a00808f10a7.html