Exam Code: 400-101 (Practice Exam Latest Test Questions VCE PDF)
Exam Name: CCIE Routing and Switching (v5.0)
Certification Provider: Cisco
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2021 Jun 400-101 Study Guide Questions:

Q41. Which two statements about OSPFv3 are true? (Choose two.) 

A. It supports unicast address families for IPv4 and IPv6. 

B. It supports unicast address families for IPv6 only. 

C. It supports only one address family per instance. 

D. It supports the use of a cluster ID for loop prevention. 

E. It supports multicast address families for IPv4 and IPv6. 

F. It supports multicast address families for IPv6 only. 

Answer: A,C 

Q42. Packets from a router with policy-based routing configured are failing to reach the next hop. 

Which two additions can you make to the router configuration to enable the packets to flow correctly? (Choose two.) 

A. Enable ip proxy-arp on the exiting interface. 

B. Specify the next hop as an address. 

C. Specify the next hop as an interface. 

D. Add a match-any permit statement to the route map. 

Answer: A,B 


Here is an example: 

Router(config)#route-map Engineers permit 20 

Router(config-route-map)#match ip address 2 

Router(config-route-map)#set interface Ethernet1 

Here, instead of specifying a next-hop, it specifies that any packets matching this rule will be forwarded directly out the interface Ethernet1. This means that either the destination device must be on this segment, or there must be a router configured with Proxy ARP that can forward the packet to the ultimate destination. 

Q43. Which type of EIGRP routes are summarized by the auto-summary command? 

A. internal routes that are learned from a peer that is outside the range of local network statements 

B. external routes that are learned from a peer that is inside the range of local network statements 

C. locally created routes that are outside the range of local network statements 

D. external routes that are learned from a peer that is outside the range of local network statements 

Answer: B 


Auto-Summarization of External Routes 

EIGRP will not auto-summarize external routes unless there is a component of the same major network that is an internal route. To illustrate, let us look at Figure 15. 

Router Three is injecting external routes to and into EIGRP using the redistribute connected command, as shown in the configurations below. 

Router Three 

interface Ethernet0 

ip address 

interface Ethernet1 

ip address 

interface Ethernet2 

ip address 

!router eigrp 2000 

redistribute connected 


default-metric 10000 1 255 1 1500 

With this configuration on Router Three, the routing table on Router One shows: 

one# show ip route is subnetted, 2 subnets 

D [90/11023872] via, 00:02:03, Serial0 

C is directly connected, Serial0 is subnetted, 1 subnets 

D EX [170/11049472] via, 00:00:53, Serial0 

D EX [170/11049472] via, 00:00:53, Serial0 

Although auto-summary normally causes Router Three to summarize the and routes into one major net destination (, it does not do this because both routes are external. However, if you reconfigure the link between Routers Two and Three to, and add network statements for this network on Routers Two and Three, the auto-summary is then generated on Router Two. 

Router Three 

interface Ethernet0 

ip address 

interface Ethernet1 

ip address 

interface Serial0 

ip address 

router eigrp 2000 network 

Now Router Two generates the summary for 

two# show ip route 

D is a summary, 00:06:48, Null0 

And Router One shows only the summary routE. 

one# show ip route is subnetted, 1 subnets 

C is directly connected, Serial0 

D [90/11023872] via, 00:00:36, Serial0 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/16406-eigrp-toc.html 


Updated yahoo video error 400-101:

Q44. Refer to the exhibit. 

Which statement about this device configuration is true? 

A. The NMS needs a specific route configured to enable it to reach the Loopback0 interface of the device. 

B. The ifindex of the device could be different when the device is reloaded. 

C. The device will allow anyone to poll it via the public community. 

D. The device configuration requires the AuthNoPriv security level. 

Answer: B 


One of the most commonly used identifiers in SNMP-based network management applications is the Interface Index (ifIndex) value. IfIndex is a unique identifying number associated with a physical or logical interface. For most software, the ifIndex is the name of the interface. Although relevant RFCs do not require that the correspondence between particular ifIndex values and their interfaces be maintained across reboots, applications such as device inventory, billing, and fault detection depend on this correspondence. Consider a situation where a simple monitoring software (like MRTG) is polling the interface statistics of the router specific serial interface going to the internet. 

As an example, you could have these conditions prior to re-initialization: 

physical port ifIndex 

ethernet port 

tokenring port 

serial port 

Therefore, the management application is polling the ifIndex 3, which corresponds to the serial port. 

After the router re-initialization (reboot, reload and so on) the conditions change to something similar to this: 

physical port 


ethernet port 

tokenring port 

serial port 

The management application continues polling the ifIndex 3, which corresponds now to the ethernet port. Therefore, if the management application is not warned by a trap, for example, that the router has been rebooted, the statistics polled could be completely wrong. 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/simple-network-management-protocol-snmp/28420-ifIndex-Persistence.html 

Q45. If two OSPF type 3 prefixes have the same metric, and are within the same process, which prefix(es) are installed into the routing table? 

A. The route whose originator has the lower router ID. 

B. Both routes are installed. 

C. The route whose originator has the higher router ID. 

D. The first route that is learned. 

Answer: B 


OSPF allows multiple equal-cost paths to the same destination. Since all link-state information is flooded and used in the SPF calculation, multiple equal cost paths can be computed and used for routing, and each route will be installed in the routing table. 

Q46. A GRE tunnel is down with the error message %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing error. 

Which two options describe possible causes of the error? (Choose two.) 

A. Incorrect destination IP addresses are configured on the tunnel. 

B. There is link flapping on the tunnel. 

C. There is instability in the network due to route flapping. 

D. The tunnel mode and tunnel IP address are misconfigured. 

E. The tunnel destination is being routed out of the tunnel interface. 

Answer: C,E 


The %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing error message means that the generic routing encapsulation (GRE) tunnel router has discovered a recursive routing problem. This condition is usually due to one of these causes: 

. A misconfiguration that causes the router to try to route to the tunnel destination address using the tunnel interface itself (recursive routing) 

. A temporary instability caused by route flapping elsewhere in the network 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/22327-gre-flap.html 


High value ccie 400-101 questions:

Q47. Refer to the exhibit. 

You have configured two routing protocols across this point-to-point link. How many BFD sessions will be established across this link? 

A. three per interface 

B. one per multicast address 

C. one per routing protocol 

D. one per interface 

Answer: D 


Cisco devices will use one Bidirectional Forwarding Detection (BFD) session for multiple client protocols in the Cisco implementation of BFD for Cisco IOS Releases 12.2(18)SXE, 12.0(31)S, and 12.4(4)T. For example, if a network is running OSPF and EIGRP across the same link to the same peer, only one BFD session will be established, and BFD will share session information with both routing protocols. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/fs_bfd.html#wp1053749 

Q48. Which statement about NAT64 is true? 

A. It uses one-to-one mapping between IPv6 addresses and IPv4 addresses. 

B. It requires static address mapping between IPv6 addresses and IPv4 addresses. 

C. It can be used to translate an IPv6 network to another IPv6 network. 

D. It can be configured for stateless and stateful translation. 

Answer: D 

Q49. Which two statements describe characteristics of HDLC on Cisco routers? (Choose two.) 

A. It supports multiple Layer 3 protocols. 

B. It supports multiplexing. 

C. It supports only synchronous interfaces. 

D. It supports authentication. 

Answer: A,C 


Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for sending data over synchronous serial links using HDLC. Cisco HDLC also provides a simple control protocol called Serial Line Address Resolution Protocol (SLARP) to maintain serial link keepalives. Cisco HDLC is the default for data encapsulation at Layer 2 (data link) of the Open System Interconnection (OSI) stack for efficient packet delineation and error control. The absence of a protocol type field in the HDLC header posed a problem for links that carried traffic from more than one Layer 3 protocol. Cisco, therefore, added an extra Type field to the HDLC header, creating a Cisco-specific version of HDLC. Cisco routers can support multiple network layer protocols on the same HDLC link. For example an HDLC link between two Cisco routers can forward both IPv4 and IPv6 packets because the Type field can identify which type of packet is carried inside each HDLC frame. 

Reference: http://www.cisco.com/c/en/us/td/docs/routers/access/800/819/software/configuration/Guide/ 


Q50. Which statement about the VLAN database is true? 

A. Manually deleting the vlan.dat file can cause inconsistency in the database. 

B. Private VLAN information is stored in the database. 

C. VLAN configurations 1 through 4096 are stored in the vlan.dat file. 

D. The VLAN database is used only if the VTP domain name in the VLAN database matches the VTP domain name in the startup-config file. 

Answer: A