4A0-101 Sample Questions Answers

Use split horizon by default.

Send information about directly connected links to neighbors at periodic intervals.

Use holddown timers when topologies change to allow for convergence.

Maintain multiple databases: neighbor, topology and routing.

The CE routers run only IPv6.

The PE routers must run IPv4 and IPv6.

The P routers must run IPv4 and IPv6.

IPv6 routes on the PE routers may have an IPv4 address as the next hop.

A BDR is always required on point-to-point links.

The second highest RID is always the BDR.

The BDR only listens for link-state updates sent to 224.0.0.5.

The BDR always acknowledges link-state updates from the DR

The primary and backup routes are to the same destination.

The primary and backup routes appear in the routing table.

The backup route is configured with a higher preference value.

The next-hop of the primary and backup routes are different.

Option A

Option B

Option C

Option D

'asbr' is missing from router R1's configuration.

Router R1 needs to have an export policy added to it.

Router R5 does not have an export policy for these prefixes.

Router R1 needs to have an import policy added to it.

The IPv6 header has a header checksum field, header length field and no fragmentation offset field.

The IPv6 header has no header checksum field, no header length field and does have a fragmentation offset field.

The IPv6 header has a header checksum field, no header length field and no fragmentation offset field.

The IPv6 header has no header checksum field, no header length field and no fragmentation offset field.

0

1

2

3

4

AS External

Inter-Area Prefix

Inter-Area Router

Intra-Area Prefix

Convergence is triggered when the adjacency between routers R1 and R2 drops as a result of hello timeouts.

Convergence is triggered when the physical interfaces between routers R1 and R2 go down.

Convergence will not be triggered because switches cannot run routing protocols between them.

Convergence is triggered when the switches notify the routers about the link-state info.

Convergence is triggered when an LSA is sent from router R1 to router R2 to indicate that the link is down.

Show ospf neighbors

Show router ospf neighbors

Show router ospf adjacency

Show ospf adjacency

224.0.0.5

224.0.0.6

224.0.0.9

224.0.0.10

RIPv2 does not have support for multicast

Router LSA

Network LSA

Summary Network LSA

Summary Router LSA

They are type 7 within the area and are not modified at the ABR

They are type 5 within the area and converted to type 3 at the ABR

They are type 5 within the area and are not modified at the ABR

They are type 7 within the area and converted to type 5 at the ABR

RIPv2 supports basic and MD5 authentication only.

RIPv2 supports password and MD5 authentication only.

RIPv2 does not support authentication, password and MD5 authentication.

RIPv2 does not support authentication.

IS-IS routers exchange updates by sending UDP packets to a multicast address.

IS-IS routers exchange updates using IP multicast packets.

IS-IS routers exchange updates using Ethernet multicast packets.

IS-IS routers exchange updates by sending packets to the subnet broadcast address.

IOM

CPM

FIB

SPF

One

Two

Three

Four

When a Link State Update is received in response to a Link State Request

When a router receives a Hello packet from a neighbor that contains its router id in the neighbor list

When OSPF neighbors exchange Database Descriptor packets

When a Link State Acknowledgement is received in response to a Link State Update

In multi-access networks, a DR and BDR are elected only if there are more than two routers connected to the network segment.

In multi-access networks, a DR and BDR are elected only if the subnet masks on the router interfaces are less than /30

In multi-access networks, a DR and BDR are elected. To ensure resiliency, both the DR and BDR send link-state advertisements describing the network.

In multi-access networks, a DR and BDR are elected. The DR sends link-state advertisements describing the network.

Area ID

Hello and Dead Intervals

Stub flag

DR and BDR addresses

The list of neighbors

Default path

Default gateway

Gateway path

Proxy ARP

True

False

Area Border Router

Autonomous System Boundary Router

Designated Router

All routers within an OSPF area.

30 second network updates

Classless routing

Broadcast advertisement

Poison Reverse

No protocol extensions required

Only supported by OSPF and IS-IS

Transparent to routing neighbors

Uses Graceful Restart to inter-operate with other vendors

DSCP marking

Class of Service Marking

DSAP marking

ICMP type

An L1 adjacency will be formed.

An L1/L2 adjacency will formed

L2 adjacency will be formed

No adjacency will be formed

Router R4 will have a route to router R6's system address with router R2 as the next-hop.

Router R4 will have a default route with router R2 as the next-hop.

Router R4 will have a default route with router R3 as the next-hop.

Router R4 will not have a route that can be used to reach the system address of router R6.

Data traffic from network 192.168.1.0/24 to 192.168.3.0/24 will be forwarded through router R2.

Data traffic from network 192.168.3.0/24 to 192.168.1.0/24 will be forwarded through router R2.

The system interface of routers R1 and R3 must be included into OSPF for traffic to flow between the 192.168.1.0/24 and 192.168.3.0/24 networks.

The OSPF adjacency between router R1 and router R3 is operationally down.

The route policy should be applied as an import policy.

The route policy should say "from protocol isis" instead of "from protocol direct".

The ASBR configuration should be removed.

The interface between routers R1 and R3 must be in OSPF area 0.

10.10.10.2

10.10.10.3

10.10.10.4

10.10.10.6

There is no ASBR configured in the network.

Router LSA

Network LSA

Intra-Area Prefix LSA

Link LSA

Next Header

Traffic Class

Flow Label

Payload Length

Options

Exchange

Up

Down

2-Way

Router R1 generates a Type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a Type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a Type 4 LSA that is flooded to areas 0 and 2.

Router R3 generates a Type 4 LSA that is flooded to area 0, and router R6 generates a Type 4 LSA that is flooded to area 2.

R1 has one IS-IS adjacency and one LSP.

R1 has one IS-IS adjacency and two LSPs.

R1 has one IS-IS adjacency and four LSPs.

R1 has two IS-IS-adjacencies and two LSPs

R1 has two IS-IS adjacencies and four LSPs

The LSP is acknowledged by sending a PSNP PDU.

The LSP is acknowledged by sending an LSP PDU.

The LSP is acknowledged by sending a Hello PDU.

LSP are not acknowledged on broadcast links. The DIS sends periodic CSNPs to maintain database synchronization

The routing information base (RIB).

The routing table manager (RTM).

The equal cost multipath configuration (ECMP).

The forwarding information base (FIB).

The link state database (LSDB).

ping static 10.5.5.5

ping static 0.0.0.0/0

ping 10.5.5.5

ping 0.0.0.0

AFI

IDI

HO-DSP

NSEL

Exchange

Up

Down

2-Way

The router installs two routes for the destination with two different next hops. A hashing algorithm is used to distribute traffic over the two paths.

The router installs two routes for the destination with two different next hops. Traffic is evenly distributed over the two paths.

The router installs four routes for the destination with four different next hops. A hashing algorithm is used to distribute traffic over the four paths.

The router installs four routes for the destination with four different next hops. Traffic is evenly distributed over the four paths.

The router installs one route for the destination. Traffic is evenly distributed over the two paths.

The area addresses TLV

The intermediate system neighbors TLV

The IP interface address TLV

The authentication information TLV

224.0.0.5

224.0.0.6

The unicast IP address of the interface the update is sent on

The system address of the router.

A packet with a destination anycast address is sent to all nodes on the local link.

A packet with a destination anycast address is sent to all nodes on the local network.

A packet with a destination anycast address is sent to all nodes that have joined the anycast group.

A packet with a destination anycast address is sent to the nearest node that is assigned the anycast address

A packet with a destination anycast address is sent to all nodes that are assigned the anycast address.

Route redistribution is only needed if Internet access is a requirement.

Route filtering is the process of attaching data path filters to router interfaces.

Route filtering involves deciding whether to permit or deny certain routing updates from being accepted into, or distributed out of, the route-selection process.

Redistribution is needed for exchanging routes from one routing protocol to another.

OSPF routers that are redistributing routes must be configured as ABRs.

From the least significant 32 bits of the chassis MAC address.

From the most significant 32 bits of the chassis MAC address.

From the loopback IP address.

By using the command "config router router-id X.X.X.X"

From the system IP address.

From the highest interface IP address.

The system ID

The loopback address

The sequence number of the Hello packet

The device that first initiated communication becomes the DIS

The highest interface MAC address

Configuring IS-IS interfaces

Enabling IS-IS

Configuring level capabilities

Specifying an area address

To support classful routing protocols.

To allow IP routes to be defined using any number of bits for the network portion of the address.

To allow interdomain routing between an IGP and EGP such as OSPF and BGP.

To simplify the allocation of IP address space by defining a fixed size for the network portion of the address for each of the address classes.

An OSPF database description packet has not been received from the neighbor.

The interface facing the neighbor is down.

The interface is included in a different area than the neighbor router.

The router has not received a valid OSPF Hello packet from its neighbor.

ff00::1:2

fe80::216:4dff:fe13:5cae

::ffff:0:0.240.0.0.1

2001:db8::30a:216:4dff:fe13:5cae

fd01:2234:5678::1

When a router receives updates from its neighbors, it adds them to its link state database, performs an SPF computation, and sends the results to its neighbors.

An SPF computation is done by each router to determine the best path to destination networks. All the best paths determined by the SPF calculation will be seen in the route table.

Each router constructs its own link state database with updates received from neighbors.

An SPF computation is done by each router to determine the best path to destination networks. All the best paths determined by the SPF calculation will be offered to the route table manager.

Router R3's routing table can only contain one of the routes, which will result in route flapping.

Router R3's routing table will have one entry for 10.1.1.0/24 and one entry for 10.1.2.0/24.

The networks will be represented with one entry of 10.0.0.0/8 in router R3's routing table.

The networks will be represented with one entry of 10.0.0.0/24 in router R3's route table.

Router R1 generates a type 5 LSA that is flooded through all OSPF areas.

Router R1 generates a type 7 LSA that is flooded through all OSPF areas.

Router R1 generates a type 5 LSA that is flooded through area 1. Router R2 generates a type 7 LSA that is flooded through areas 0 and 2.

Router R1 generates a type 7 LSA that is flooded through area 1. Router R3 generates a type 5 LSA that is flooded through areas 0 and 2.

traceroute 10.2.3.1

traceroute 10.2.3.1 next-hop 10.1.2.1

traceroute next-hop 10.1.2.1

traceroute does not work on the Alcatel-Lucent 7750 SR.

traceroute 10.1.2.1

An L1/L2 router can have neighbors in different areas.

An L1/L2 router calculates separate SPF trees for the Level 1 and Level 2 topology.

An L1/L2 router advertises its L2 routes to its L1 neighbors.

An L1/L2 router sets the ATT bit in L1 LSPs to identify itself as an L1 router.

Router R1 generates a type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a type 4 LSA that is flooded to areas 0, 1, and 2.

Router R3 generates a type 4 LSA that is flooded to areas 0 and 2.

Router R3 generates a type 4 LSA that is flooded to area 0, and router R6 generates a type 4 LSA that is flooded to area 2.

ping static 10.5.5.5

ping static 0.0.0.0/0

ping 10.5.5.5

ping 0.0.0.0

Configure IS-IS interfaces

Enable IS-IS

Configure level capabilities

Specify an area address

Not so stubby area

Stub area

Backbone area

Normal area

1

49

47

45

39

Fast reroute capability

Control traffic prioritization

Route redistribution

Traffic engineering extensions

Cut through forwarding

An OSPF type 3 LSA is an intra-area LSA, generated by the ABR only when route summarization is configured.

An OSPF type 3 LSA is an inter-area LSA, generated by the ABR only when route summarization is configured.

An OSPF type 3 LSA is an inter-area LSA, generated by an ASBR to describe external routes.

An OSPF type 3 LSA is an inter-area LSA, generated by the ABR to describe a route to neighbors outside the area.

Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3- R2-R5-R6).

Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R2-R5-R6).

Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).

Router R6 to router R3 will follow (R6-R5-R7-R4-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).

Option A

Option B

Option C

Option D

Metric is based on hop count.

Slow convergence after link failures.

Support hierarchy through the use of areas.

Support for CIDR.

Link state updates sent using layer 3 multicast.

L1 routers

L2 routers

L1/L2 routers

L1 and L2 routers

10.10.10.99

10.10.10.66

10.10.10.2

10.10.10.1

Not so stubby areas

Level1 area WC

Stub areas

Partially stubby areas

Level 2 areas

The corporate head office router will have a default route and the branch site will have a more specific static route.

The corporate head office router and the branch office router will both have specific static routes.

The corporate head office router and the branch router will both have default routes.

The corporate head office router will have a more specific static route and the branch office router will have a default route.

CSNPs are used to maintain consistency in the link state database.

CSNPs are advertised before an adjacency is formed with another router.

There are two types of CSNPs: Level 1 and Level 2.

CSNPs are advertised after an adjacency is formed with another router.

Fast reroute capability.

Control traffic prioritization.

Route redistribution.

Traffic engineering extensions.

Cut through forwarding.

To give IPv6 traffic preferential routing over IPv4 routes.

To allow core routers running only IPv6 protocols to carry IPv4 traffic.

To give IPv4 only routers the ability to route based on IPv6 addresses.

To allow IPv6 traffic to pass through an IPv4 network.

Down

Initializing

2-way

Full

Link

Intra-Area Prefix

Inter-Area Prefix

Inter-Area Router

CSNPs are used to maintain consistency in the Link-State database.

CSNPs are advertised before an adjacency is formed with another router.

There are two types of CSNPs: Level 1 and Level 2.

The CSNP lists the LSPs in the router's database

A Type 3 LSA is generated by an ASBR only when route summarization is configured.

A Type 3 LSA is generated by an ABR only when route summarization is configured.

A Type 3 LSA is generated by an ASBR to describe routes to routers outside the area.

A Type 3 LSA is generated by an ABR to describe routes to routers outside the area.

The current DR is selected, if there is one. Otherwise, the router with the lowest priority is the DR. If priorities are the same, the DR is chosen based on the lowest RID.

The current DR is selected, if there is one. Otherwise, the router with the highest priority is the DR. If priorities are the same, the DR is chosen based on the highest RID.

The router with the lowest priority is the DR. If priorities are the same, the current DR is selected. Otherwise the DR is chosen based on the lowest RID.

The router with the highest priority is the DR. If priorities are the same, the current DR is selected. Otherwise the DR is chosen based on the highest RID.

config> static-route 0.0.0.0/0 next-hop 10.1.2.2

config>router> static-route 0.0.0.0 255.255.255.255 next-hop 10.1.2.1

config>router> static-route 0.0.0.0/0 next-hop 10.1.2.2

config>router> static-route 0.0.0.0/0 next-hop 10.1.2.1

A route from IS-IS.

A route from OSPF.

A floating static route.

A static route.

Use an import policy and a prefix list on router R2.

Use an export policy and a prefix list on router R1.

Use an import policy and a prefix list on router R1.

Router R1 cannot discard the route because IS-IS does not support import policies.

Next Header

Traffic Class

Hop Limit

Fragment Offset

Flow Label

FE80::203:FAFF:FEAC:77AF/64

2000::203:FAFFFEAC:77AF/64

FE80::3FAFF:FEAC:77AF/64

FC00::203:FAFF:FEAC:77AF/64

FC00::3:FAFF:FEAC:77AF/64

Normal

Stub

Totally stubby

Totally NSSA

Add the "originate-default-route" option in the NSSA area configuration on router R3.

Add the "summaries" option to the NSSA area configuration on router R1.

Configure a static route on router R1 to 192.168.3.1.

Configure a default route on router R2.

1

2

3

4

6

7

Router R2 sends an update to 224.0.0.5 on its broadcast and point-to-point interfaces. The DR does not send any updates.

Router R2 sends an update to 244.0.0.5 on its point-to-point interfaces. The DR sends an update to 224.0.0.6 on the broadcast network.

Router R2 sends an update to 224.0.0.5 out its point-to-point interfaces and an update to 224.0.0.6 out its broadcast interface. The DR sends updates to 224.0.0.5 on the broadcast network.

Router R2 sends an update to 224.0.0.6 out its point-to-point interfaces and an update to 224.0.0.5 out its broadcast interface. The DR sends an update to 224.0.0.6 on the broadcast networks.

The router's system address.

The next-hop prefix.

The interface's global prefix.

The next-hop system address.

AS External

Intra-Area Prefix

Inter-Area Router

Inter-Area Prefix