Which consideration is the most important for the network designer when considering IP routing?
C. on-demand routing
Explanation: Convergence is most important because with delayed convergence outage recovery will be delayed as well.
You want to gather as much detail as possible during a network audit, to include data time
stamping across a large number of interfaces, customized according to interface, with a minimal
impact on the network devices themselves. Which tool would you use to meet these
D. Cisco Discovery Protocol
NetFlow provides extremely granular and accurate traffic measurements and a high-level
collection of aggregated traffic. The output of netflow information is displayed via the show ip
cache flow command on routers. The Table shows a description of the fields for NetFlow output.
Table. Netflow Output description
DataQuirk is a web-based medical transcription company for exotic-animal veterinarians. The
company recently added a third ISP for international business. They are organizing the enterprise
network into a fully operational Enterprise Edge.
To which two modules will the three ISPs be directly related? (Choose two)
B. E- Commerce
D. Edge Distribution
E. Internet Connectivity
F. Remote Access VPN
Explanation: The purpose of ISP link is for serving customers & it is also providing internet
connectivity to internal & external users, thus it falls into above 2 categories.
The Enterprise Edge Module consists of the following modules:
+ E-commerce modulE. includes the devices and services necessary for an organization to
provide e-commerce applications.+ Internet connectivity modulE. provides enterprise users with
Internet access.+ VPN and remote access modulE. terminates VPN trafc and dial-in connections
from external users.+ WAN/ MAN and site-to-site modulE. provides connectivity between remote
sites and the central site over various WAN technologies.
In these modules, only E-Commerce and Internet Connectivity modules will be directly related to
the three ISPs.
Which two of these practices are considered to be best practices when designing the access layer for the enterprise campus? (Choose two)
A. Implement all of the services (QoS, security, STP, and so on) in the access layer, offloading the work from the distribution and core layers.
B. Always use a Spanning Tree Protocol; preferred is Rapid PVST+.
C. Use automatic VLAN pruning to prune unused VLANs from trunked interface to avoid broadcast propagation.
D. Avoid wasted processing by disabling STP where loops are not possible.
E. Use VTP transparent mode to decrease the potential for operational error
When designing the building access layer, you must consider the number of users or ports
required to size up the LAN switch. Connectivity speed for each host should also be considered.
Hosts might be connected using various technologies such as Fast Ethernet, Gigabit Ethernet, or
port channels. The planned VLANs enter into the design.
Performance in the access layer is also important. Redundancy and QoS features should be
The following are recommended best practices for the building access layer:
• Limit VLANs to a single closet when possible to provide the most deterministic and highly
• Use Rapid Per-VLAN Spanning Tree Plus (RPVST+) if STP is required. It provides the faster
convergence than traditional 802.1d default timers.
• Set trunks to ON and ON with no-negotiate.
• Manually prune unused VLANs to avoid broadcast propagation (commonly done on the
• Use VLAN Trunking Protocol (VTP) Transparent mode, because there is little need for a
common VLAN database in hierarchical networks.
• Disable trunking on host ports, because it is not necessary. Doing so provides more security and
speeds up PortFast.
• Consider implementing routing in the access layer to provide fast convergence and Layer 3 load
• Use the switchport host commands on server and end-user ports to enable PortFast and
disable channeling on these ports.
• Use Cisco STP Toolkit, which provides
• PortFast: Bypass listening-learning phase for access ports
• Loop GuarD. Prevents alternate or root port from becoming designated in absence of bridge
protocol data units (BPDU)
• Root GuarD. Prevents external switches from becoming root
• BPDU GuarD. Disables PortFast-enabled port if a BPDU is received
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 3, Page 85
With deterministic Wireless LAN Controller redundancy design, the different options available to
the designer have their own strengths. Which one of these statements is an example of such a strength?
A. Dynamic load balancing, or salt-and-pepper access point design, avoids the potential impact of
oversubscription on aggregate network performance.
B. N+N redundancy configuration allows logically grouping access points on controllers to
minimize intercontroller roaming events.
C. N+N+1 redundancy configuration has the least impact to system management because all of
the controllers are collocated in an NOC or data center
D. N+1 redundancy configuration uses Layer 3 intercontroller roaming, maintaining traffic on the
same subnet for more efficiency.
Explanation: With such an arrangement there is no complex mesh of access points & controllers.
N+N WLC Redundancy
With N+N redundancy, shown in Figure 5-14. an equal number of controllers hack up each other.
For example, a pair of WLCs on one floor serves as a backup to a second pair on another floor.
The top WLC is primary for API and AP2 and secondary for AP3 and AP4. The bottom WLC is
primary for AP3 and AP4 and secondary for API and AP2. There should be enough capacity on
each controller to manage a failover situation.
N+N+1 WLC Redundancy
With N+N+1 redundancy, shown in Figure 5-15, an equal number of controllers back up each
other (as with N+N), plus a backup WLC is configured as the tertiary WLC for the APs. N+N+1
redundancy functions the same as N+N redundancy plus a tertiary controller that backs up the
secondary controllers. The tertiary WLC is placed in the data center or network operations center