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- CCNA Routing and Switching 200-105
71.
Which of the following is the most likely technology used for an access link to a
Metro Ethernet service?
- A.100Base-LX10
- B.High-speed TDM (for example, T3, E3)
- C.MPLS
- D.100Base-T
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| Metro Ethernet uses Ethernet access links of various types. Time-division multiplexing (TDM) links such as serial links, even higher-speed links like T3 and E3, do not use Ethernet protocols, and are less likely to be used. MPLS is a WAN technology that creates a Layer 3 service. Two answers refer to Ethernet standards usable as the physical access link for a Metro Ethernet service. However, 100Base-T supports cable lengths of only 100 meters, so it is less likely to be used as a Metro Ethernet access link in comparison to 100BaseLX10, which supports lengths of 10 km. |
72.
An enterprise uses a Metro Ethernet WAN with an Ethernet LAN (E-LAN) service,
with the company headquarters plus ten remote sites connected to the service. The
enterprise uses EIGRP at all sites, with one router connected to the service from each
site. Which of the following are true about the Layer 3 details most likely used with
this service and design? (Choose two answers.)
- A.The WAN uses one IP subnet.
- B.The WAN uses ten or more IP subnets.
- C.A remote site router would have one EIGRP neighbor.
- D.A remote site router would have ten EIGRP neighbors
- Answer & Explanation
- Report
Answer : [A and D]
Explanation :
Explanation :
| An E-LAN service is one in which the Metro Ethernet service acts as if the WAN were a single Ethernet switch, so that each device can communicate directly to every other device. As a result, the routers sit in the same subnet. With one headquarters router and ten remote sites, each router will have ten EIGRP neighbors. |
73.
An enterprise uses an MPLS Layer 3 VPN with the company headquarters connected
plus ten remote sites connected to the service. The enterprise uses EIGRP at all sites,
with one router connected to the service from each site. Which of the following are
true about the Layer 3 details most likely used with this service and design? (Choose
two answers.)
- A.The WAN uses one IP subnet.
- B.The WAN uses ten or more IP subnets.
- C.A remote site router would have one EIGRP neighbor.
- D.A remote site router would have ten or more EIGRP neighbors.
- Answer & Explanation
- Report
Answer : [B and C]
Explanation :
Explanation :
|
A Layer 3 MPLS VPN creates an IP service with a different subnet on each
access link. With one headquarters router and ten remote sites, 11 access links exist,
so 11 subnets are used. As for the EIGRP neighbor relationships, each enterprise router has a neighbor relationship with the MPLS provider edge (PE) router, but not with any of the other enterprise (customer edge) routers. So each remote site router would have only one EIGRP neighbor relationship. |
74.
Which of the following answers is most accurate about access link options for an
MPLS network?
- A.Uses only TDM (T1, T3, E1, E3, etc.)
- B.Uses only Ethernet
- C.Uses only DSL and cable
- D.Uses a wide variety of Layer 1 and Layer 2 networking technologies
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| Architecturally, MPLS allows for a wide variety of access technologies. Those include TDM (that is, serial links), Frame Relay, ATM, Metro Ethernet, and traditional Internet access technologies such as DSL and cable. |
75.
An enterprise connects 20 sites into an MPLS VPN WAN. The enterprise uses OSPF
for IPv4 routes at all sites. Consider the OSPF area design options, and the PE-CE
links. Which of the following answers is most accurate about OSPF areas and the
PE-CE links?
- A.The PE-CE link may or may not be chosen to be in backbone area 0.
- B.The PE-CE link must not be in the backbone area 0.
- C.The PE-CE link must be in the backbone area 0.
- D.The PE-CE link will not be in any OSPF area.
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| The PE-CE link is the link between the customer edge (CE) router and the MPLS provider’s provider edge (PE) router. When using OSPF, that link will be configured to be in some area. OSPF design allows for that link to be in the backbone area, or not, through the use of the OSPF super backbone, which exists between all the PE routers. |
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