2021 Apr 400-101 practice exam

Q31. Which technology facilitates neighbor IP address resolution in DMVPN? 

A. CEF 

B. mGRE 

C. a dynamic routing protocol 

D. NHRP 

Answer: D 

Explanation: 

NHRP Used with a DMVPN 

NHRP is used to facilitate building a VPN and provides address resolution in DMVPN. In this context, a VPN consists of a virtual Layer 3 network that is built on top of an actual Layer 3 network. The topology you use over the VPN is largely independent of the underlying network, and the protocols you run over it are completely independent of it. The VPN network (DMVPN) is based on GRE IP logical tunnels that can be protected by adding in IPsec to encrypt the GRE IP tunnels. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_4/ip_addr/configuration/guide/hadnhrp.html#w p1057255 


Q32. Which two statements about MLD are true? (Choose two.) 

A. MLD is a subprotocol of ICMPv6. 

B. When a single link supports multiple interfaces, only one interface is required to send MLD messages. 

C. MLD is a subprotocol of PIMv6. 

D. When a single link supports multiple interfaces, all supported interfaces are required to send MLD messages. 

E. There are three subtypes of MLD query messages. 

F. The code section in the MLD message is set to 1 by the sender and ignored by receivers. 

Answer: A,B 


Q33. Which two options are the two main phases of PPPoE? (Choose two.) 

A. Active Discovery Phase 

B. IKE Phase 

C. Main Mode Phase 

D. PPP Session Phase 

E. Aggressive Mode Phase 

F. Negotiation Phase 

Answer: A,D 

Explanation: 

PPPoE is composed of two main phases: 

Active Discovery Phase — In this phase, the PPPoE client locates a PPPoE server, called an access concentrator. During this phase, a Session ID is assigned and the PPPoE layer is established. 

PPP Session Phase — In this phase, PPP options are negotiated and authentication is performed. Once the link setup is completed, PPPoE functions as a Layer 2 encapsulation method, allowing data to be transferred over the PPP link within PPPoE headers. 

Reference: http://www.cisco.com/c/en/us/td/docs/security/asa/asa92/configuration/vpn/asa-vpn-cli/vpn-pppoe.html 


Q34. DRAG DROP 

Drag and drop each STP port role on the left to the matching statement on the right. 

Answer: 


Q35. A company has just opened two remote branch offices that need to be connected to the corporate network. Which interface configuration output can be applied to the corporate router to allow communication to the remote sites? 

A. interface Tunnel0 

bandwidth 1536 

ip address 209.165.200.230 255.255.255.224 

tunnel source Serial0/0 

tunnel mode gre multipoint 

B. interface fa0/0 

bandwidth 1536 

ip address 209.165.200.230 255.255.255.224 

tunnel mode gre multipoint 

C. interface Tunnel0 

bandwidth 1536 

ip address 209.165.200.231 255.255.255.224 

tunnel source 209.165.201.1 

tunnel-mode dynamic 

D. interface fa 0/0 

bandwidth 1536 

ip address 209.165.200.231 255.255.255.224 

tunnel source 192.168.161.2 

tunnel destination 209.165.201.1 

tunnel-mode dynamic 

Answer: A 


Q36. DRAG DROP 

Drag and drop the TACACS+ configuration command on the left to the correct function it performs on the right. 

Answer: 


Q37. Which two options are benefits of EIGRP OTP? (Choose two.) 

A. It allows EIGRP routers to peer across a service provider without the service provider involvement. 

B. It allows the customer EIGRP domain to remain contiguous. 

C. It requires only minimal support from the service provider. 

D. It allows EIGRP neighbors to be discovered dynamically. 

E. It fully supports multicast traffic. 

F. It allows the administrator to use different autonomous system numbers per EIGRP domain. 

Answer: A,B 

Explanation: 

EIGRP Over the Top (OTP) allows EIGRP routers to peer across a service provider infrastructure without the SP’s involvement. In fact with OTP, the provider won’t see customer routes at all. EIGRP OTP acts as a provider-independent overlay that transports customer data between the customer’s routers. To the customer, the EIGRP domain is contiguous. A customer’s EIGRP router sits at the edge of the provider cloud, and peers with another EIGRP router a different location across the cloud. Learned routes feature a next hop of the customer router — not the provider. Good news for service providers is that customers can deploy EIGRP OTP with their involvement 

Reference: http://ethancbanks.com/2013/08/01/an-overview-of-eigrp-over-the-top-otp/ 


Q38. Which component of MPLS architecture uses protocols such as the label distribution protocol and tag distribution protocol to exchange labels? 

A. control plane 

B. data plane 

C. forwarding plane 

D. routing plane 

Answer: A 


Q39. A TCP/IP host is able to transmit small amounts of data (typically less than 1500 bytes), but attempts to transmit larger amounts of data hang and then time out. What is the cause of this problem? 

A. A link is flapping between two intermediate devices. 

B. The processor of an intermediate router is averaging 90 percent utilization. 

C. A port on the switch that is connected to the TCP/IP host is duplicating traffic and sending it to a port that has a sniffer attached. 

D. There is a PMTUD failure in the network path. 

Answer: D 

Explanation: 

Sometimes, over some IP paths, a TCP/IP node can send small amounts of data (typically less than 1500 bytes) with no difficulty, but transmission attempts with larger amounts of data hang, then time out. Often this is observed as a unidirectional problem in that large data transfers succeed in one direction but fail in the other direction. This problem is likely caused by the TCP MSS value, PMTUD failure, different LAN media types, or defective links. 

Reference: http://www.cisco.com/c/en/us/support/docs/additional-legacy-protocols/ms-windows-networking/13709-38.html 


Q40. Which two statements about the command distance bgp 90 60 120 are true? (Choose two.) 

A. Implementing the command is a Cisco best practice. 

B. The external distance it sets is preferred over the internal distance. 

C. The internal distance it sets is preferred over the external distance. 

D. The local distance it sets may conflict with the EIGRP administrative distance. 

E. The internal distance it sets may conflict with the EIGRP administrative distance. 

F. The local distance it sets may conflict with the RIP administrative distance. 

Answer: C,F 

Explanation: 

To allow the use of external, internal, and local administrative distances that could be a better route than other external, internal, or local routes to a node, use the distance bgp command in address family or router configuration mode. To return to the default values, use the no form of this command. distance bgp external-distance internal-distance local-distance no distance bgp 

. Syntax Description 

external-distance 

Administrative distance for BGP external routes. External routes are routes for which the best path is learned from a neighbor external to the autonomous system. Accept table values are from 1 to 255. The default is 20. Routes with a distance of 255 are not installed in the routing table. 

internal-distance 

Administrative distance for BGP internal routes. Internal routes are those routes that are learned from another BGP entity within the same autonomous system. Accept table values are from 1 to 255. The default is 200. Routes with a distance of 255 are not installed in the routing table. 

local-distance 

Administrative distance for BGP local routes. Local routes are those networks listed with a network router configuration command, often as back doors, for that router or for networks that are being redistributed from another process. Accept table values are from 1 to 255. The default is 200. Routes with a distance of 255 are not installed in the routing table. 

Defaults 

external-distance: 20 

internal-distance: 200 

local-distance: 200 

In this case, the internal distance is 60 and the external is 90, and the local distance is 120 (same as RIP). 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfbgp1. html#wp1113874