Answer: C,E 

Answer: B 

Explanation: 

The local routes have the administrative distance of 0. This is the same adminstrative distance as connected routes. However, when you configure redistributed connected under any routing process, the connected routes are redistributed, but the local routes are not. This behavior allows the networks to not require a large number of host routes, because the networks of the interfaces are advertised with their proper masks. These host routes are only needed on the router that owns the IP address in order to process packets destined to that IP address. 

It is normal for local host routes to be listed in the IPv4 and IPv6 routing table for IP addresses of the router's interfaces. Their purpose is to create a corresponding CEF entry as a receive entry so that the packets destined to this IP address can be processed by the router itself. These routes cannot be redistributed into any routing protocol. 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/ip-routing/116264-technote-ios-00.html 

Answer: A,B 

Explanation: 

The IP prefix is a member of the IPv4 address family. After the PE device learns the IP prefix, the PE converts it into a VPN-IPv4 prefix by combining it with an 8-byte route distinguisher (RD). The generated prefix is a member of the VPN-IPv4 address family. It uniquely identifies the customer address, even if the customer site is using globally nonunique (unregistered private) IP addresses. The route distinguisher used to generate the VPN-IPv4 prefix is specified by a configuration command associated with the virtual routing and forwarding (VRF) instance on the PE device. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_l3_vpns/configuration/15-mt/mp-l3-vpns-15-mt-book/mp-bgp-mpls-vpn.html 

Answer: A,B,C 

Explanation: 

IS-IS is an Interior Gateway Protocol (IGP) for routing OSI. IS-IS packets are not encapsulated in CLNS or IP but are encapsulated directly in the data-link layer. The IS-IS protocol family is OSI, and values such as 0xFE and 0xFEFE are used by the data-link protocol to identify the Layer 3 protocol as OSI. 

Reference: http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a00800a3e6f.sh tml 

Answer: A,C,F 

Explanation: 

A. RIP requires a seed metric to be specified when redistributing routes into that protocol. A seed metric is a "starter metric" that gives the RIP process a metric it can work with. The OSPF metric of cost is incomprehensible to RIP, since RIP's sole metric is hop count. We've got to give RIP a metric it understands when redistributing routes into that protocol, so let's go back to R1 and do so. 

C. Filtering routes is another explanation, if the routes to R2 are boing filtered from being advertised to R1. 

F. If the metric is offset to 16, then the routes will have reached the maximum hop count when redistributed to RIP. The max hop count for RIP is 16. 

Answer: A,B 

Explanation: 

When dealing with the possibility of routing updates making their way back into an AS, BGP relies on the information in the AS_path for loop detection. An update that tries to make its way back into the AS it was originated from will be dropped by the border router. With the introduction of route reflectors, there is a potential for having routing loops within an AS. A routing update that leaves a cluster might find its way back inside the cluster. Loops inside the AS cannot be detected by the traditional AS_path approach because the routing updates have not left the AS yet. BGP offers two extra measures for loop avoidance inside an AS when route reflectors are configured. 

Using an Originator ID 

The originator ID is a 4-byte, optional, nontransitive BGP attribute (type code 9) that is created by the route reflector. This attribute carries the router ID of the originator of the route in the local AS. If, because of poor configuration, the update comes back to the originator, the originator ignores it. 

Using a Cluster List 

The cluster list is an optional, nontransitive BGP attribute (type code 10). Each cluster is represented with a cluster ID. 

A cluster list is a sequence of cluster IDs that an update has traversed. When a route reflector sends a route from its clients to nonclients outside the cluster, it appends the local cluster ID to the cluster list. If the route reflector receives an update whose cluster list contains the local cluster ID, the update is ignored. This is basically the same concept as the AS_path list applied between the clusters inside the AS. 

Reference: http://borg.uu3.net/cisco/inter_arch/page11.html 

Answer: C 

Answer: A,C,E 

Explanation: 

Bridge Assurance is enabled by default and can only be disabled globally. Also, Bridge Assurance can be enabled only on spanning tree network ports that are point-to-point links. 

Finally, both ends of the link must have Bridge Assurance enabled. 

With Bridge Assurance enabled, BPDUs are sent out on all operational network ports, including alternate and backup ports, for each hello time period. If the port does not receive a BPDU for a specified period, the port moves into the blocking state and is not used in the root port calculation. Once that port receives a BPDU, it resumes the normal spanning tree transitions. 

Reference: 

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guid e/cli/CLIConfigurationGuide/SpanningEnhanced.html 

Answer: C 

Answer: A,B