CCIE OEQ

Here are some important Open Ended Questions one should know.

This book is highly recommended by Top CCIE’s for passing the OEQ Section of the CCIE Lab Exam:

CCIE Routing and Switching Exam Certification Guide (4th Edition)

As of May 10th 2010, the OEQ Section has been removed from the R&S CCIE Lab Exam…….Thank God!

Additional Sections for OEQ

IPv6 CCIE OEQ Section

General Questions:

What is the “local-as” community? Local-as is used in confederations to prevent confederation peers from exporting routes outside of the confederation AS.
What is the difference between “join-group” and “static-group” in Multicast? “static-group” does not cause the device to process the multicast packets themself, it will forward the multicast packets out the interface. “join-group” would process switch the group.
What is the difference between FECN & BECN? FECN is used to notify a router that there is a remote router causing congestion in the network. BECN is used to notify a router that it is the router causing congestion in the network.
Using Access-lists, what happens when a time-range ACL is inactive? When the acl is inactive, this means that the acl is not within the time range specified and the acl is not being used. Traffic passes as if there was no acl applied.
What is the difference between log & log-input in a ACL? These options apply to an individual ACE in an ACL and cause packets that match the ACE to be logged. The log-input option goes further and enables logging of the ingress interface and source mac address in addition to the packet’s source and destination addresses and ports.
What does RIPv2 use to calculate its metric? hop count.
What is the purpose of the Route Tag Field in a RIPv2 message? You can use the route tag to distinguish between internal and external RIP routes.
What is the RIPng multicast destination address? FF02::0009
How does RIP prevent Loops? RIP uses split-horizon where it will not advertise routes back through the same interface it received them on. In addition, it uses poison-reverse, hop count and hold-down timers.
How does EIGRP detect neighbor failures. Explain? EIGRP sends small hello packets every 5 seconds by default with a hold-time of 3 times the hello interval on all media except for NBMA interfaces which is 60 second Hello.
How does OSPF detect neighbor failures. Explain? OSPF sends hello packets by default every 10 seconds on Ethernet segments and 30 seconds on Non-Broadcast segments with a hold-time of 4 times the Hello interval.
How does BGP detect neighbor failures. Explain? BGP uses keepalives by default every 60 seconds with a hold-time of 180 seconds. You can manually set these and BGP will negotiate the timers between peers.
How does RIPv2 detect neighbor failures. Explain? RIP sends route updates every 30 seconds. If the route update is not heard of within 180 seconds, the routes are marked unusable. If there is still no update after 240 seconds then the routes are removed from routing table.
On Frame-relay networks, what can cause EIGRP/OSPF neighbor relationship to fail? In Frame-relay, you need to add the “broadcast” keyword in the frame-relay map otherwise use the “neighbor” statement in OSPF/EIGRP.
With the Link Status displaying “UP”and the Protocol displaying “DOWN” on a frame relay connection, what can be the cause of this? You can have an LMI or clock rate mismatch
What would prevent the exchange of LMIs on Frame-Relay? Keepalives are disabled.
What are LMIs? Local Management Interface, virtual circuit status messages, provide communication and synchronization between frame relay dte/dce devices.
How do you load-balance traffic across unequal-cost paths in EIGRP? EIGRP uses the variance command. You would find the successor route and multiply it by the variance. The result metric would be the maximum metric allowed for routes to be successor routes and traffic would load-balanced over them unequally.
How many paths can EIGRP load balance over by default? 4
How do you limit how much bandwidth EIGRP can use per interface? Use the “ip bandwidth-percent” command. By default EIGRP will use up to 50%.
What packets does EIGRP acknowledge? Updates, Queries and Replies. Hello’s are not ACK’ed.
What are the EIGRP metric weights and which one is not used in the metric calculation? bandwidth,delay,load,reliability and mtu. MTU is not used in the calculation.
How does EIGRP prevent Loops? EIGRP uses the DUAL algorithm for selecting successor and feasible successor routes.
What does SIA mean in EIGRP? SIA is “stuck in active”. When routes go down Query messages are sent to EIGRP neighbors asking about these networks. If the neighbor fails to reply within 3 minutes, it is said to be SIA. The router then clears the non-responsive neighbor.
How many attempts will EIGRP make for a query to a non responsive neighbor? 16
Does EIGRP support the use of secondary addresses? EIGRP hello messages come from the primary interface address and therefore can cause neighbor adjacency problems if used incorrectly.
What is the administrative distance of an EIGRP summary route? 5
What LSA type is used in NSSA OSPF Area? LSA Type 7
Which types of LSA’s are filtered in Stub and Totally Stubby Areas? Type 4,5 Lsa’s are filtered in Stub Areas and type 3,4,5 Lsa’s are filtered in Totally Stubby Areas.
In OSPF, which command is used to show DR/BDR? “show ip ospf neighbor”
Why is a DR used in Ethernet Lan Environments? Routers in an ethernet lan share the network segment and using a DR prevents each router from forming a link with every other router resulting in many unnecessary links. Instead the DR manages all of the advertisements on the lan segment.
What is the function of an OSPF ASBR? It is a gateway between external protocols, where you inject routing information from other protocols.
Does OSPF use split-horizon? OSPF uses split horizon in a sense that LSAs cannot be flooded back through the ABR.
What is the type 4 LSA? Its an LSA sent out by the ABR to advertise the ASBR address.
How do you disable split horizon in OSPF? You setup Stub or NSSA areas.
How do you calculate the default metric in OSPF? 10 to the 8 power divided by the interface bandwidth. Use “auto-cost reference-bandwidth” to change this on each OSPF router.
Which OSPF Areas do not allow External Routes? All Stub Areas which include Stub, Totally Stubby, NSSA and Totally Stubby NSSA.
What are the four different OSPF Route Types? Inter, Intra, External Type 1 and External Type 2
What are the four different OSPF Router Types? Internal, ABR,ASBR,Backbone
What are the four different OSPF Area Types? Backbone, Standard, Stub, Totally Stub
How does OSPF send out updates? OSPF floods lsas over all interfaces in the same area except for the interface it came in on.
What are OSPF Fast Hello Packets? Hello packets configured to be sent at an interval of less than 1 second, configure the dead-interval minimal hello-multiplier.
Which LSA is used by the Designated Router? LSA Type 2
How does the DR and BDR get elected in OSPF? The router with highest priority is elected DR and second runner up is BDR. If priority is equal among all, then router with Highest Router-id, etc. Router-id is manually entered or is selected from Highest Loopback Interface, if there is no loopback interface then highest Active Interface IP address is used as Router-ID.
Explain what an OSPF neighbor is versus an OSPF adjacency. OSPF neighbors are routers connected on the same network segment running OSPF and adjacencies are links between these neighbors sharing LSAs.
Explain how Hello Packets are sent over virtual-links? Hello packets are sent to establish connectivity of the Virtual Link but then are suppressed once the link is up. Virtual links are configured as demand circuits.
How many equal cost paths can OSPF load balance traffic on? Default is set to 4 equal cost paths, maximum of 16 is allowed.
What is BGP synchronization? The rules states that if an AS provides transit to another AS, the routes within that AS need to be learned via an IGP otherwise the routes will not be advertised to peering AS’s. This is because a router in an AS that is not running BGP will blackhole routes that are forwarded to it. The non BGP running routers can only forward routes that are in its routing table, therefore, the non-bgp router needs to have these routes added in via IGP.
What BGP attributes can influence inbound traffic? Med (Metric) and AS-Path
What BGP attribute can influence outbound traffic? Weight and Local Preference
What BGP attributes are required between neighbors? Origin, next-hop and AS-Path
When would you use an extended ACL in BGP? When you want to filter out more specific networks and match only exact source addresses.
What is the AS-SET in BGP? Its an attribute used in the summary command to show as-paths that are part of the summary.
Whats the administrative distance for BGP? 200 for iBGP and 20 for eBGP
What is the range of Private BGP AS numbers? 64512 - 65535
Explain the different states BGP routers can be in? Idle State (waiting for tcp connection), Connect State (connecting via tcp), Active State (tcp connection does not complete), OpenSent State (connection completed, received Open message), OpenConfirm State (waiting for keepalive), Established State (exchanging update packets)
In BGP, what is an atomic aggregate? This is an attribute used to inform downstream bgp routers that some AS path information is lost mainly from aggregating certain routes and other routes can be more reliable.
What are BGP communities used for? Communities are 32 bit extra attributes you can attach to bgp routes to apply specific policies.
How does BGP prevent routing Loops? Internally, iBGP peers do not advertise routes that have been learned from iBGP peers to other iBGP peers. Externally, eBGP routers do not accept routes with its own AS in AS-Path.
What is a solicited-node multicast address?
What is an ipv6 solicit-node used for?
What are the default STP 802.1d timers for Hello, Forward delay and Max-age? Hello = 2 sec, Forward delay = 15 sec and Max-Age = 20 sec.
What are the 802.1d Port States? Blocking, Listening, Learning, Forwarding and Disabled.
What is the difference between WRR and SRR? shaped/shared round robin is used as a queuing mechanism for both input and output queues on 3560/3750 switches while weighted round robin is used as a queuing mechanism for 3550 switch output queues.
Using the MQC, up to how many policers can be nested? max of 3 can be nested
What is the default snmp version used? Version 1
Which snmp version provides encryption and authentication? Version 3
What is the difference between Stacker and Predictor? Stacker is more CPU intensive but better on memory utilization and predictor guesses the next sequence of characters int he data stream and is less CPU intensive but hard on memory.
How do you change the EIGRP metric K values? Under EIGRP process, “metric weights 0 1 1 0 0 0″
What types of QOS Service models are there? Best-Effort, Integrated services and Differentiated Services.
How is PQ in LLQ different from Legacy PQ? PQ in LLQ is limited to fewer traffic classes and is policed so that traffic in LLQ cannot starve out other traffic classes.
What is classification in terms of QoS? Its a way to differentiate a traffic flow which can be used for specific policies.
How is WRED different from RED? Both of these help prevent tcp synchronization by randomly dropping selected packets before the queue becomes full. The main difference between them is that WRED has the capability of differentiating between high and low priority traffic while RED does not. You can setup different profiles for traffic with WRED.
What kind of configuration options are there for shaping? Generic Traffic shaping (GTS), Frame-Relay traffic shping (FRTS) and Class based shaping.
What is PHB in QoS? Per hop behavior
What is CBWFQ in QoS? Class based weighted fair queuing, a feature that guarantees bandwidth for user-defined traffic classes. The traffic is guaranteed atleast this amount of bandwidth.
What is WFQ in QoS? Weighted Fair Queuing helps reduce response time by moving certain traffic to the front of the queue and fairly shares bandwidth between high bandwidth flows.
When using the rate-limit command, what does the “continue” command do? Evaluates the next rate-limit command
What happens when the RP fails in a “sparse-dense mode” network? The network fails over to a dense mode network for the source/receiver.
How is RPF used in Multicast networks? RPF, reverse path forwarding, is used to check the path that the multicast flow came in on and only allow that path to be used.
What is the scope of the Multicast range? 224.0.0.0 - 239.255.255.255
How does sparse-mode differ from dense-mode? Dense mode performs implicit joins and uses flood and prune method, source trees. Sparse mode uses an RP and builds distribution trees and later changes to a source tree if a better path exists between send/receiver.
In Multicast, when a router communicates with a switch, what protocol can it use? CGMP or IGMP
In Multicast, when a router communicates between another router, what protocol does it use? PIM
What are two ways to discover an RP? Use Auto-RP or Bootstrap Protocol
Can Auto-RP be used in a “sparse-mode” configuration? Yes but “autorp listener” has to be enabled on each router.
What is the PIM SPT-Threshold? Tells the router to change to the source tree between the sender/receiver after an x amount of bandwidth in kbps. Can use “infinite” to prevent changing from shared tree to source tree.
What is IGMP? Internet Group Management Protocol used between hosts/routers to track the multicast groups of which hosts are members.
Explain the process that happens when a host requests a Multicast stream.
How does IGMP differ between version 1 & 2 ? IGMPv2 introduces a leave message, configurable max response time and a querier election process.
What is the difference between IGMP snooping and CGMP?
Explain RPT and SPT. In sparse mode, the source registers with the RP and the RP with the receiver using the RPT (root path tree). The routers switchover to the SPT (shortest Path tree) by default, after the first packet received from the shared tree. The SPT makes the path between the sender/receiver more efficient.
What kind of PIMv2 Dense mode messages would you expect to see? Hello, Join & Prune, Graft & Graft Ack and Assert messages.
What kind of PIMv2 Sparse mode messages would you expect to see? Hello, candidate rp advertisement, Join & Prune, Assert, Register and Register Stop messages.
What happens when you have a PIMv2 router and Pimv1 router in a multicast network?
How does the Designated Forwarder get elected? The forwarder is the router with the highest IP address on the network and the lowest metric to the source.
How does the Designated Router become elected in Multicast Networks? Check Priority, else the highest IP address.
What is anycast? Communication between a single sender and the nearest of a group of receivers.
What is MSDP? Its a protocol that allows an RP in a given AS to share information about active sources in other AS’s. Allows multicast data to be forwarded between different AS’s.
What effect does the TTL have on a packet? It prevents the packet from being routed forever.
Which field in the IP packet is used for QoS? The ToS (Type of Service)
What is the use of a redirect? ICMP redirect messages are used by routers to notify the hosts on the data link that a better route is available for a particular destination.
Define Administrative Distance. Measure used by routers when there are more than two paths to a destination using two or more routing protocol. AD defines the reliability of the protocol.
What layer of the OSI model are Cisco Security features used? OSI layer 1 - 5
Why would you use the subnet-zero? When subnetting, the first network obtained after subnetting the network address is subnet zero. Using the command subnet-zero allows us to use this network in addressing.
What is an Autonomous System? Its a network under a common administration or routing domain.
When is uRPF used? When you want to limit spoofed addresses on interfaces usually coming from external connections. It verifies the reachability of the source.
What is the purpose of using GRE in IPv6? With GRE tunnels you can transition from an IPv4 network to IPv6 network by tunneling (encapsulating IPv6) over IPv4 network. This will allow communication between two IPv6 endpoints.
What is the IPv6 Neighbor Discovery Redirect Function? This is used by the router to inform a host that there is a better path to send datagrams for a given destination.
How would you secure DHCP in your network? You can use DHCP snooping. Setup Trust state for trusted DHCP Servers and untrusted for all other ports except trunks.
What is the fragment offset in an IP packet? It makes sure ip packets can be reassembled in the correct order since not all packets may arrive in the same sequence.
What is the function of flow control? It manages the rate of data transmission between two nodes.
What is CIDR? Classless Inter Domain Routing, used to assign IPs without using the standard IP Classes (A,B,C)
What is TCP Intercept used for? Features used to prevent syn flood attacks.
Whats the difference between snmp traps and snmp informs? Informs are traps that request confirmation of receipt.
What is MVR? Multicast Vlan Registration, allows a host to subscribe/unsubscribe to a multicast stream over a networkwide multicast vlan.
What is the MVR feature should be enabled on single device ports? mvr immediate, ability to send an immediate leave message
What is SSM? Source Specific Multicast, uses multicast range 232.0.0.0/8 by default. Uses IGMPv3 which allows a source to explicitly request traffic from an S,G pair using INCLUDE report, joining directly to the source without using the RP
What is ODR? On Demand Routing, uses CDP to propagate the ip prefix, used in frame-relay network(hub and spoke), does not use routing protocols so the only way it transfers prefixes is by CDP
How do you enable ODR on point-to-multipoint interfaces? Enable CDP, by default its disabled on these interfaces.
Which protocol number is ICMP? Protocol number 1
What does ICMPv6 ND use to prevent hosts from assigning the same IP address? Feature called duplicate address detection
What is OSPF Graceful Restart? Also known as “non-stop forwarding”, a feature that increases availability of the network by allowing OSPF routers stay on the forwarding path even when OSPF is restarted.
What does an IPv6 link local prefix look like? FE80::/10
What are the different states HSRP can be in? Initial, Learn, Listen, Speak, Standby and Active
What is the SPEAK state in HSRP? Router sends periodic hello messages and actively participates in the election of the active/standby router.
What is the LISTEN state in HSRP? The router knows the virtual IP address but the router is neither the active router nor the standby router. It basically “listens” for hello messages.
The Active Virtual Gateway is part of which fault-tolerant default gateway technology? GLBP
GLBP uses what type of messages between peers? Uses hello messages every 3 seconds to the multicast address of 224.0.0.102
What does a cluster command switch use to discover member switches? CDP
What are method lists in AAA? These lists define ways authentication and accounting will be performed and the sequence these will be performed in.
What happens when the VTP password does not match between switches? Switches cannot exchange vlan information
Whats ports does the DHCP protocol use? Clients use Source UDP 68(Client) and Destination UDP 67(Server); Servers use Source UDP 67(Server) and Destination UDP 68(Client)
What are the violation modes of port-security and their meanings? Protect: drops packets with unknown source addresses until you remove sufficeint number of secure MAC addresses to drop below the maximum value. Restrict: Similiar to Protect but it also causes the Security violation counter to increment. Shutdown: Puts interface in error-disabled state and sends SNMP trap notification.
How does PfR compute its best path? PfR bases on the Performance(latency,packet loss, reachibility, throughput,jitter), Load sharing and link usage and cost minimization
What are the advantages of MSTP? Multiple STP allows multiple spanning-tree instances to be mapped to a single instance reducing the number of spanning-tree instances needed in a large vlan network.
What are the advantages of RSTP? Rapid spanning-tree provides rapid convergence of the spanning tree as compared to the original 802.1d. COnvergence can be as fast as 1 second as compared to 50 seconds. Portfast, Uplinkfast and Backbonefast have been implemented into RSTP.
What are the differences between 802.1q and ISL? 802.1q is an industry standard vlan tagging protocol inserting a 4 byte header between the source mac and ethertype of the frame while ISL is cisco proprietary adding a 26 byte header and a 4 byte trailer encapsulating the frame adding additional overhead as compared to 802.1q.
What is an Assert message? PIM Assert messages are used on Multi-access networks (LAN) to elect a router responsible for forwarding multicast traffic for the given lan. This is to prevent duplication of multicast traffic since RPF will succeed due to the nature of multi access networks. Router wins based on best AD, best metric and lastly highest IP address.
When configuring BGP peering to loopback interfaces between confederation peers, do you still need to use the “ebgp-multihop x” command? Yes
What are BGP confederations? Confederations are used in larger BGP networks in order to reduce the number of iBGP peering sessions.
During times of no congestion, will traffic in the low latency queue be allowed to exceed its configured amount? Yes and at times of congestion, exceeded priority traffic will be dropped.
On a Gigabit Link Connection between a 3560 switch and a PC, if the PC is manually set to 100/FULL and the switchport is set to 100/FULL, what is the outcome? There will be flapping on the switchport and the PC will never get a connection.
How do you enable fragmentation on Multilink interfaces? Fragmentation is enabled by default.
In OSPF, what type of authentication is Type 0? Type 0 authentication is no authentication.
If you need to load balance traffic over EIGRP links and you are not showing a feasible successor route, what can you do? Modify the “delay” on links that you would like as feasible successor. The advertised distance would need to be less than the feasible distance of the successor route.
In OSPFv3, what type of IPv6 address is needed for the neighbor command to send unicast instead of multicast messages? Use the link local address
What is proxy-arp? When a router receives an arp request for an IP that is not on that network, the router will reply its its own MAC Address if it has a route for the destination.
What is the interface level command used to convert a broadcast into a multicast? ip multicast helper-map broadcast [group] [acl]
With the following command, “random-detect 5 60 90 4″. What does the 4 represent? This represents the Mark Probabiliy. It means that when there are 90 packets in the queue, 1 out of 4 packets will be dropped.
Without applying an ACL to an interface, how else can you prevent traffic from passing through the router? You can match the traffic with class-map and drop it in a policy-map that is applied to that interface.
What command would you use on a 3560 switch to create a macro for a range of interfaces? define interface-range [MACRO_NAME] [Interface range]
What happens when a superior BPDU enters an interface with Root guard enabled? The port gets marked root-inconsistent and it gets blocked.
What command can you use to troubleshoot communication between Cisco devices? Debug
When configuring Authentication keys for RIP or EIGRP, what type of clock notation is used when setting send and accept lifetimes? Military Time
What needs to be modified in order for switchport startup delay to be 16 seconds? Change the forward-time to 8 seconds on the root bridge switch. Listening-8sec + Learning-8sec = 16 seconds.
How do you disable spanning-tree on an interface without using the “no spanning-tree” commands? “spanning-tree bpdufilter enable” on the interface level
How do you advertise a default route to a peer in EIGRP? On the interface connecting to the peer, you can use “ip summary-address eigrp xxx 0.0.0.0 0.0.0.0″
What is the benefit of MVR? It reduces the duplication of multicast traffic across multiple vlans in layer 2 networks by centralizing the distribution of multicast traffic into a single VLAN. The forwarding behavior of MVR allows traffic to cross between different data vlans.
What command will prevent RIP from sending out broadcasts or multicasts on any interfaces? passive-interface
What command will suppresses the incoming and outgoing updates on EIGRP interfaces? passive-interface
What does the command “ip inspect name CHK http audit-trail on” do? When applied to the interface, it collects http statistics
What is the correct Switch parameter setting when a host is manually set for 100/Full? 100/Full
What is the correct Switch parameter setting when a host is manually set for 1000/Full? 1000/Full or AUTO
What is Protocol 59? Ipv6 No next header, indicates that there is nothing following the header.
While 2 paths exist to destination X, what can prevent one path from becoming a feasible successor? The advertised distance of this non-successor path can be higher than the feasible distance of the successor route hence preventing this route from becoming a feasible successor route.
How do you release/renew a DHCP assigned IP address on a router? # release dhcp interface x/x and renew dhcp interface x/x
What kind of feature can you enable on your router that will reduce the impact reloads may have on your routing topology and suppress advertisements for given amount of time? Dampening
What type of PIM mode should you use to flood and prune when an RP is not available? ip pim spare-dense mode
How would you use the interface-range macro called TRUNK? interface range macro TRUNK
What is the default OSPF metric-type of a redistributed route? E2 - External type 2
What type of routes are advertised by default when enabling “eigrp stub” command on a router? connected and summary.
What is “ip bgp-community new-format”? This command changes the default BGP format to AA:NN to conform to RFC 1997
What is the minimum syslog logging level needed when using the “log” option in an ACL for logging to a monitoring host? logging level 6 - informational
What is the DSCP EF value? 46
How do you enable VLAN based QoS on a 3560/3750 switch? First you enable “mls qos” globally, then you enable “mls qos vlan-based” on the ports that will participate in the QoS and lastly you apply the service-policy on the switched virtual interface. The ports will inherit all QoS configurations from their respective SVIs.
What’s the significance of a Aggregate Policer? It applies to multiple traffic classes on a single interface. You create the policer rate/burst globally and later enter it into a policy-map for different classes. All classes share this policer’s rate/burst on that interface.
Which Multicast Address is used to notify all PIM Routers? 224.0.0.13
By default, if you need to change Eigrp’s metric but cannot alter the bandwidth, what can you do? Change the delay on the interface.
Which IPv6 tunnel method uses the prefix 2002::/16? Automatic 6to4
In IPv6, what is the “Next Header Field” ? This field is used to chain together the headers in an IPv6 datagram.
Whats the difference between Active and Passive when it comes to EIGRP? Active is when a topology change occurs and a given route is not found while Passive indicates that a given route exists.
What is the lowest timing interval that you can use for Frame-Relay Traffic Shaping? 10ms
What is the administrative distance for ODR? 160
What is the role of the PIM Dense Mode State Refresh Feature? Its keeps the pruned state in Dense mode from timing out which saves bandwidth by reducing the reflooding of unwanted multicast traffic.
What is the prefix and prefix-length of a link local address? fe80::/10
When configuring port security, what is the default violation mode? shutdown
What can you enable to have a port re-enable itself after 2 minutes if it recently violated a port security maximum limit? Configure errdisable recovery feature.
What happens when the Multicast threshold on a switchport with Storm-Control enabled is exceeded? All traffic including unicast, broadcast and multicast is dropped.
What is the purpose of the “ip ospf demand-circuit” interface level command? This command suppresses periodic hellos and lsa refreshes. LSA refreshes are only sent when there is a topology change or the other router does not support this feature.
How would you write an IPv6 prefix that matches any route with a prefix length of 64 or less? ipv6 prefix-list MYPREFIX permit ::/0 le 64
What would an as-path access-list look like if you need to match all rotes from AS300 and its directly connected customers? ip as-path access-list 10 permit ^300(_[0-9]+)?$
What are 2 ways to add the question mark ( ? ) to a password? Hold down CNTRL + V and type ? or press ESC and press Q followed by the ? mark.
What role does “priority” play in GLBP? It determines who will be the AVG (Active Virtual Gateway) responsible for answering ARP requests.
If the AVG fails in a three router GLBP configuration and all routers have the same configured priority, who will win the election? The router with the highest IP address.
What happens when you plug in a switch with no VTP domain configured? First domain the switch hears whether it is client or server, it accepts it.
What happens when you enable DHCP snooping on a private vlan? It is enabled on the primary vlan and propagates to the secondary vlans.
How is spanning-tree affected by private vlans? STP is enabled on the Primary vlan, secondary vlans do not run an STP instance.
What is the purpose of the max-age timer in STP? This is the amount of time the switch takes before performing an STP recalculation.
During the Root-bridge election, if a switch hears a superior BPDU, what happens? The switches own BPDU is ceased and the superior BPDU is forwarded.
How do UDLD normal and aggresive modes work? For unidirectional link failures, normal mode sends a syslog message while aggressive mode attempts to reconnect once a second until 8 seconds and then error disables the port.
If OSPF and EIGRP both receive a route for the same network and OSPF administrative distance is set to 90, which protocol is the tie breaker? EIGRP as it takes the original AD.
What router feature polls the SNMP MIB variables locally and does not waste resources on SNMP queries? RMON
RouterA connects to RouterB over two different speed links. LinkA=100Mbps and LinkB=10Mbps. We know that LinkA will become the successor, but will LinkB become the feasible successor? Yes it will.
You summarize 150.1.0.0/16 on RouterA toward RouterB. RouterA creates a summary route for null0. What is the Administrative Distance of this summary route on RouterA and RouterB? RouterA=5 and RouterB=90
You enter a static route to null0. What is the administrative distance for this null0 route? 1
You are in charge of Autonomous System 200 and your AS is between AS100 and AS300. Instead of using any access-lists, prefix-lists or as-path access-lists, how can you prevent your AS from becoming a transit? Use communities to set routes from AS100 & AS300 as “no-export”.
What multicast prefix range does SSM use by default? 232.0.0.0/8
What is the “no-redistribution” command used for when configuring an NSSA area? It prevents external routes which are translated into type 7 lsa from entering the NSSA area.
What will the “no-redistribution” and “no-summary” commands for Area 1 Nssa accomplish? External routes will be rejected while a default route will be allowed into Area 1.
What does “frame-relay qos-autosense” enable? Enhanced Local Management Interface
You enable vlan 1-100 on MST instance 1, vlan 101-200 on MST instance 2 and vlan 201-300 on MST instance 3, what vlans are enabled for MST instance 0? Vlans 301-4094
What do you need to configure in order for NSSA to not allow type 3 lsa? no-summary
In order for OSPF to detect failure within 1 second, what needs to be changed? ospf dead-interval set to 1 second.
Loopback interfaces are assigned what network type by default? stub
What is the maximum metric allowed for a reachable network in RIP? 15
Which of the ospf network types is Cisco proprietary? Point-to-multipoint non-broadcast
RIPv2 multicasts updates to which udp port? 520
What BGP ORIGIN code is the most preffered? IGP
How often are PIM hellos sent out? 30 seconds
Which multicast address is the “all routers on this subnet” address? 224.0.0.2
PIM uses which multicast address to send Hello’s to neighbors? 224.0.0.13
Which port is used by SNMP to send traps? udp 162
How many port states does 802.1w have? 3, Learning, Forwarding and Discarding.
On Portfast enabled ports, if you connect a device, how long will it take for the port to start forwarding? It forwards right away.
802.1w default hello time is? 2 seconds
What are the frame-relay LMI types? cisco,ansi and q933a
How often are LMI keepalives sent? 10 seconds
Which end of a serial link should the clock rate be set on? DCE
Frame-relay traffic-shaping is enabled but there is no map-class configured, what is the default Bc for the dlci? Based on the 56k speed, it would be 56000/8= 7000
How many hold queues are automatically configured when priority queuing is utilized? 4
How many classes can be defined using either priority queuing or custom queuing? 64
What happens when multiple priority queues(LLQs) are configured in a policy-map? IOS places all LLQs in one internal LLQ and schedules on first come first serve.
What type of WRED is configured by issuing “random-detect” without any trailing commands in a policy-map? Wred based on IP Precedence
Which command signifies a “single rate, three color policer” when configuring policing on an router interface? violate-action
Which command signifies a “dual rate, three color policer” when configuring policing on a rouer interface? PIR
Which device in the Frame-relay network sets the FECN bit? the frame-relay switch
For dot1q tunnels, what should the switch system MTU be set to? 1504
What makes a neighbor internal BGP (iBGP)? Neighbor is in the same AS
If the BGP router-id is not set and there is no loopback configured, how will BGP determine its router-id? Highest IP of an up/up interface
Which BGP message is used to negotiate the keepalive timer between two BGP peers? Open message
Which BGP message is sent when an error occurs between BGP peers? Notification
What is the purpose of the route-map option on a network statement in BGP configuration? It can be used to filter routes and manipulate Path Attributes
With auto-summary enabled, you need to inject the loopback interface 150.1.4.0/24 into BGP without using the “mask” command. What would your network command look like? network 150.1.0.0
With auto-summary enabled, you redistribute your connected interfaces which contain loopback 150.1.4.0/24. What is the network output of the bgp table after redistribution? 150.1.0.0
You create a default static route that points to null0. You redistribute static into BGP but your neighbors complain that they do not see the default route. Why? default-information originate is missing from BGP configuration
You are aggregating routes on R5 with the as-set option. Some of the routes have been redistributed. What is the ORIGIN code for the aggregate route? a question mark “?” for Incomplete
What type of message does one BGP peer send to another BGP peer when it has routes to advertise? Update message
Name two things a route reflector checks to ensure there are no loops on updates it receives from BGP peer routers? Cluster_id and Originator_id
When working with dynamic and static group-to-RP mappings and there is an RP conflict, which keyword will ensure that the static mapping takes precedence? override
How many bits are there in a IPv6 Multicast group ID? 112
After the DHCP client sends out a broadcast DHCPDISCOVER and receives a unicast DHCPOFFER from the DHCP Server, is the DHCPREQUEST that the client sends after the offer broadcast or unicast? Broadcast
In what mode do you configure dhcp excluded addresses for a dhcp server? Router config mode
What is the default trap logging level on a Cisco router? Informational
Which SNMP version provides authentication and encryption? version 3
What type of message does an OSPF router send in response to a multicast hello? unicast hello
Other than on the interface where else can you configure the priority for an OSPF neighbor? Under Router config mode, neighbor x.x.x.x priority
Routers with all interfaces belonging within the same area and sharing a link-state database are known as? internal routers
Which LSA type lists all of a router’s links and their state and are flooded within the area they originated? type 1
Which lsa type is used to originate “O IA”? type 3
What is the default metric for a default route generated by the “default-information originate” command? 10
What does the following command achieve “nsf ietf”? OSPF graceful restart
What command would you issue to temporarily shutdown a BGP neighbor? neighbor x.x.x.x shutdown
When matching BGP regular expressions, what does the pipe symbol “|” mean? Means “or”
Which is more preferred, the origin code or the MED? origin code
What is the default BGP community used? Internet (0)
What is the command to configure community propagation to BGP neighbors? send-community
Whats is the default queuing mechanism on slow link low bandwidth connections? weighted fair queuing
Which QoS mechanism prevents global synchronization? WRED
What does the frame-relay fecn-adapt command provide? Sets the BECN bit if it receives a FECN notification of congestion
Which BGP extended community indicates which routes should be imported from MP-BGP into a VRF? Route Target
What is the default mode when configuring tcp intercept? intercept
Cisco Host performs a traceroute to RouterC which is three hops away, what type of ICMP message is sent to the traceroute application from the first hop router? time-exceeded
When configuring dot1q tunnels, what gets disabled automatically on the dot1q tunnel port? CDP
When a packet arrives with a label on the MPLS LSR, what does it use to forward the packet? LFIB
When a packet arrives unlabeled onto an MPLS LSR, what does it use to forward the packet? FIB
What is the longest Match Rule? Routing rule when there is more than one matching address, the route with longer bit sequence is used.
What triggers InARP? LMI status message triggers InARP when PVC comes up.

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