- Home
- Networking
- CCNA Routing and Switching 200-105
146.
A network uses an SDN architecture with switches and a centralized controller.
Which of the following terms describes a function or functions expected to be found
on the switches but not on the controller?
- A.A Northbound Interface
- B.A Southbound Interface
- C.Data plane functions
- D.Control plane functions
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
|
Although many variations of SDN architectures exist, they typically use a centralized controller. That controller may centralize some or even all control plane
functions in the controller. However, the data plane function of receiving messages,
matching them based on header fields, taking actions (like making a forwarding decision), and forwarding the message still happens on the network elements (switches)
and not on the controller. For the incorrect answers, the control plane functions may all happen on the controller, or some may happen on the controller, and some on the switches. The Northbound and Southbound Interfaces are API interfaces on the controller, not on the switches. |
147.
Which of the following controllers (if any) from Cisco uses a mostly centralized control plane model?
- A.Cisco Open SDN Controller
- B.Cisco Application Policy Infrastructure Controller (APIC)
- C.Cisco APIC Enterprise Module (APIC-EM)
- D.None of these controllers uses a mostly centralized control plane.
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| The Cisco Open SDN Controller uses an Open SDN model with an OpenFlow Southbound Interface as defined by the Open Networking Foundation (ONF). The ONF SDN model centralizes most control plane functions. The APIC model for data centers partially centralizes control plane functions. The APIC-EM controller (as of time of publication) makes no changes to the control plane of routers and switches, leaving those to run with a completely distributed control plane. |
148.
Host A and Host B sit in two different subnets. The path between the subnets of
these two hosts runs through three different Layer 3 forwarding devices (routers and
Layer 3 switches). A network engineer uses the APIC-EM Path Trace ACL Analysis
tool to analyze the path used for Host A to send packets to Host B. Which part of
the function is done specifically by the ACL Analysis or ACL Trace part of the tool?
- A.Discovery of the topology that exists between the two hosts
- B.Analysis of the Layer 3 forwarding decisions in the path from Host A to B
- C.Analysis of the Layer 2 forwarding decisions in the path from Host A to B
- D.Analysis of the impact of ACLs on the packets that would flow from Host A to B
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
|
APIC-EM does all the features described in the answers. APIC-EM has a built-in
function to discover the topology of a network, using a variety of protocols such as
SSH, CDP, and LLDP. Once discovered, the APIC-EM Path Trace feature analyzes the
forwarding tables on each device in comparison to a source and destination as typed
in by an APIC-EM user. Path Trace then determines the path through the network,
including the Layer 2 and Layer 3 paths. The feature that uses the name Path Trace ACL Analysis (or Path Trace ACL Trace, or a similar name) refers to the additional analysis done by APIC-EM to then compare that imaginary packet to the ACLs that exist in the network. The tool shows the ACLs and points out which ACLs would deny (that is, discard) the packet based on its current configuration. |
149.
What switch command can be used to change from PVST+ to MST ?
- A.spanning-tree mst enable
- B.no spanning-tree pvst+
- C.spanning-tree mode mst
- D.spanning-tree mst
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
150.
How many instances of STP are supported in the Cisco implementation of MST?
- A.1
- B.16
- C.256
- D.4096
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
|
|
||||||||||||||||||||||||||||
