QUESTION NO: 151

Which two functions are performed by the DR in OSPF? (Choose two.)

A. The DR originates the network LSA on behalf of the network.
B. The DR is responsible for the flooding throughout one OSPF area.
C. The DR forms adjacencies with all other OSPF routers on the network, in order to synchronize the LSDB across the adjacencies.
D. The DR is responsible for originating the type 4 LSAs into one area.
E. some packets in a flow being process-switched and others being interrupt-switched on a transit router

 

 

Answer: A,C
Explanation:

The DR originates the network LSA (LSA Type 2) which lists all the routers on the segment it is adjacent to -> A is correct.

Types 2 are ooded within its area only; does not cross ABR -> B is incorrect. The broadcast and non-broadcast network types elect a DR/BDR. They form adjacencies to all other OSPF routers on the network and help synchronize the Link State Database (LSDB) across the adjacencies -> C is correct.

LSAs Type 4 are originated by the ABR to describe an ASBR to routers in other areas so that routers in other areas know how to get to external routes through that ASBR -> D is incorrect.

 

---

QUESTION NO: 152

Refer to the exhibit.

 

AS #1 and AS #2 have multiple EBGP connections with each other. AS #1 wants all return traffic that is destined to the prefix 10.10.10.1/32 to enter through the router R1 from AS #2. In order to achieve this routing policy, the AS 1 advertises a lower MED from R1, compared to a higher MED from R3, to their respective BGP neighbor for the prefix 10.10.10.0/24. Will this measure guarantee that the routing policy is always in effect?

A. A link is flapping between two intermediate devices.A. Yes, because MED plays a deterministic role in return traffic engineering in BGP.

B. Yes, because a lower MED forces BGP best-path route selection in AS #2 to choose R1 as the best path for 10.10.10.0/24.
C. Yes, because a lower MED in AS #2 is the highest BGP attribute in BGP best-path route selection.
D. No, AS #2 can choose to alter the weight attribute in R2 for BGP neighbor R1, and this weight value is cascaded across AS #2 for BGP best-path route selection.

E. No, AS #2 can choose to alter the local preference attribute to overwrite the best-path route selection over the lower MED advertisement from AS #1. This local preference attribute is cascaded across AS #2 for the BGP best-path route selection.

 

 

Answer: E
Explanation:

MED and AS path prepending can both be used to influence the way incoming traffic from other Autonomous Systems get sent to the local AS, but they provide no guarantee as the other AS ultimately has the final word in how they send traffic. Since local preference is preferred over MED in the BGP decision process, the other AS can configure local preference to override the MED settings you have configured.

 

 

---

QUESTION NO: 153

Refer to the exhibit.

What does "(received-only)" mean?

A. The prefix 10.1.1.1 can not be advertised to any eBGP neighbor.
B. The prefix 10.1.1.1 can not be advertised to any iBGP neighbor.
C. BGP soft reconfiguration outbound is applied.
D. BGP soft reconfiguration inbound is applied.

 

 

Answer: D

Explanation:

When you configure bgp soft-configuration-inbound, all the updates received from the neighbor will be stored unmodified, regardless of the inbound policy, and these routes appear as “(receivedonly).”

 

 

---

QUESTION NO: 154

Which regular expression will only allow prefixes that originated from AS 65000 and that are learned through AS 65001?

 

A. ^65000_65001$
B. 65000_65001$
C. ^65000_65001
D. ^65001_65000$

 

Answer: D

Explanation:

The following table lists the regular expressions and their meanings:

+------------------------------------------------------+
| CHAR | USAGE |
+------------------------------------------------------|
| ^ | Start of string |
|------|-----------------------------------------------|
| $ | End of string |
|------|-----------------------------------------------|
| [] | Range of characters |
|------|-----------------------------------------------|
| - | Used to specify range ( i.e. [0-9] ) |
|------|-----------------------------------------------|
| ( ) | Logical grouping |
|------|-----------------------------------------------|
| . | Any single character |
|------|-----------------------------------------------|
| * | Zero or more instances |
|------|-----------------------------------------------|
| + | One or more instance |
|------|-----------------------------------------------|
| ? | Zero or one instance |
|------|-----------------------------------------------|
| _ | Comma, open or close brace, open or close |
| | parentheses, start or end of string, or space |
+------------------------------------------------------+
Some commonly used regular expressions include:
+-------------+---------------------------+
| Expression | Meaning |
|-------------+---------------------------|
| .* | Anything |
|-------------+---------------------------|
| ^$ | Locally originated routes |
|-------------+---------------------------|
| ^100_ | Learned from AS 100 |
|-------------+---------------------------|
| _100$ | Originated in AS 100 |
|-------------+---------------------------|
| _100_ | Any instance of AS 100 |
|-------------+---------------------------|
| ^[0-9]+$ | Directly connected ASes |
+-------------+---------------------------+

 

---

QUESTION NO: 155

Which statement describes the BGP add-path feature?

A. It allows for installing multiple IBGP and EBGP routes in the routing table.
B. It allows a network engineer to override the selected BGP path with an additional path created in the config.
C. It allows BGP to provide backup paths to the routing table for quicker convergence.
D. It allows multiple paths for the same prefix to be advertised.

 

 

Answer: D
Explanation:

BGP routers and route reflectors (RRs) propagate only their best path over their sessions. The advertisement of a prefix replaces the previous announcement of that prefix (this behavior is known as an implicit withdraw). The implicit withdraw can achieve better scaling, but at the cost of path diversity.

Path hiding can prevent efficient use of BGP multipath, prevent hitless planned maintenance, and can lead to MED oscillations and suboptimal hot-potato routing. Upon nexthop failures, path hiding also inhibits fast and local recovery because the network has to wait for BGP control plane convergence to restore traffic. The BGP Additional Paths feature provides a generic way of offering path diversity; the Best External or Best Internal features offer path diversity only in limited scenarios.

The BGP Additional Paths feature provides a way for multiple paths for the same prefix to be advertised without the new paths implicitly replacing the previous paths. Thus, path diversity is achieved instead of path hiding.

 

 

---

QUESTION NO: 156

Refer to the exhibit.

What is a reason for the RIB-failure?

A. CEF is not enabled on this router.
B. The route 10.100.1.1/32 is in the routing table, but not as a BGP route.
C. The routing table has yet to be updated with the BGP route.
D. The BGP route is filtered inbound and hence is not installed in the routing table.

 

Answer: B
Explanation:

A rib-failure occurs when BGP tries to install the bestpath prefix into the RIB, but the RIB rejects the BGP route because a route with better administrative distance already exists in the routing table. An inactive Border Gateway Protocol (BGP) route is a route that is not installed in the RIB, but is installed in the BGP table as rib-failure.

Example Topology

Router 1 (R1) and router 2 (R2) have two parallel links; one links runs BGP AS 65535 and the other link runs Enhanced Interior Gateway Routing Protocol (EIGRP) AS 1. Both BGP and EIGRP are advertising the network 10.1.1.1/32 on R1.

R2 learns about the 1.1.1.1/32 route through both EIGRP and BGP, but installs only the EIGRP route in the routing table because of the lower administrative distance. Since the BGP route is not installed in the R2 routing table, the route appears as a rib-failure in the R2 BGP table.

 

---

QUESTION NO: 157

Refer to the exhibit.

Which statement is true?

A. BGP peer 10.1.2.3 is performing inbound filtering.
B. BGP peer 10.1.2.3 is a route reflector.
C. R1 is a route reflector, but BGP peer 10.1.2.3 is not a route reflector client.
D. R1 still needs to send an update to the BGP peer 10.1.2.3.

 

Answer: D
Explanation:

On R1 the routing table version (Tbl Ver) for 10.1.2.3 is 1, other routers have version 2, so it needs to send an update to the 10.1.2.3 peer.

 

 

---

QUESTION NO: 158

Refer to the exhibit.

Router A and router B are physically connected over an Ethernet interface, and ISIS is configured as shown. Which option explains why the ISIS neighborship is not getting formed between router A and router B?

 

A. same area ID
B. same N selector
C. same domain ID
D. same system ID

 

 

Answer: D
Explanation:

With IS-IS, the LSP identifier is derived from the system ID (along with the pseudonode ID and LSP number). Each IS is usually configured with one NET and in one area; each system ID within an area must be unique.

The big difference between NSAP style addressing and IP style addressing is that, in general, there will be a single NSAP address for the entire router, whereas with IP there will be one IP address per interface. All ISs and ESs in a routing domain must have system IDs of the same length. All routers in an area must have the same area address. All Level 2 routers must have a unique system ID domain-wide, and all Level 1 routers must have a unique system ID area-wide.

 

---

QUESTION NO: 159

Refer to the exhibit.

Which statement is true?

A. There is no issue with forwarding IPv6 traffic from this router.
B. IPv6 traffic can be forwarded from this router, but only on Ethernet1/0.
C. IPv6 unicast routing is not enabled on this router.
D. Some IPv6 traffic will be blackholed from this router.

 

Answer: D

Explanation:

Here we see that the IPV6 default route shows two different paths to take, one via Ethernet 1/0 and one via Ethernet 0/0. However, only Eth 1/0 shows a next hop IPV6 address (the link local IPV6 address). There is no link local next hop addressed known on Eth 0/0. Therefore, traffic to all destinations will be load balanced over the two paths, but only half of the IPv6 traffic will be sent to the correct upsteam router.

 

 

---

QUESTION NO: 160

Refer to the exhibit.

Which statement is true?

A. IS-IS has been enabled on R4 for IPv6, single-topology.
B. IS-IS has been enabled on R4 for IPv6, multitopology.
C. IS-IS has been enabled on R4 for IPv6, single-topology and multitopology.
D. R4 advertises IPv6 prefixes, but it does not forward IPv6 traffic, because the protocol has not been enabled under router IS-IS.

 

 

Answer: A

Explanation:

When working with IPv6 prefixes in IS-IS, you can configure IS-IS to be in a single topology for both IPv4 and IPv6 or to run different topologies for IPv4 and IPv6.

By default, IS-IS works in single-topology mode when activating IPv4 and IPv6. This means that the IS-IS topology will be built based on IS Reachability TLVs. When the base topology is built, then IPv4 prefixes (IP Reachability TLV) and IPv6 prefixes (IPv6 Reachability TLV) are added to each node as leaves, without checking if there is IPv6 connectivity between nodes.

 

---

QUESTION NO: 161

Refer to the exhibit.

Why is the neighbor relationship between R2 and R4 shown as ES-IS?

A. because there is an MTU mismatch between R2 and R4
B. because interface S3/0 of R4 is configured as L1/L2
C. because interface S3/0 of R2 is configured as L1
D. because there is a hello interval mismatch between R2 and R4

 

 

Answer: C

Explanation:

With IS-IS we will see ES-IS when one of the following is true:
So in this question because we do not know about the other side’s “show CLNS neighbor” A must be the better choose.

 

---

QUESTION NO: 162

Refer to the exhibit.

The interface FastEthernet0/1 of both routers R4 and R5 is connected to the same Ethernet segment with a multicast receiver. Which two statements are true? (Choose two)

A. The device debugs all IP events for 172.16.129.4.
B. The device sends all debugging information for 172.16.129.4.
C. The device sends only NTP debugging information to 172.16.129.4.
D. The device sends debugging information every five seconds.

 

 

Answer: C,D
Explanation:

Even though R4 is the active HSRP router, traffic will flow through R5 and only R5 will send the join messages. The Multicast DR is elected by the higher IP address or priority. R5 has 192.168.2.2 and R4 has 192.168.2.1. R5 is the DR which send all packets to the RP.

 

 

---

QUESTION NO: 163

Refer to the exhibit.

This is the configuration of the ASBR of area 110.Which option explains why the remote ABR should not translate the type 7 LSA for the prefix 192.168.0.0/16 into a type 5 LSA?

 

A. The remote ABR translates all type 7 LSA into type 5 LSA, regardless of any option configured in the ASBR.
B. The ASBR sets the forwarding address to 0.0.0.0 which instructs the ABR not to translate the LSA into a type 5 LSA.
C. The ASBR originates a type 7 LSA with age equal to MAXAGE 3600.
D. The ABR clears the P bit in the header of the type 7 LSA for 192.168.0.0/16.

 

 

Answer: D

Explanation:

When external routing information is imported into an NSSA, LSA Type 7 is generated by the ASBR and it is flooded within that area only. To further distribute the external information, type 7 LSA is translated into type 5 LSA at the NSSA border. The P-bit in LSA Type 7 field indicates whether the type 7 LSA should be translated. This P-bit is automatically set by the NSSA ABR (also the Forwarding Address (FA) is copied from Type 7 LSA). The P-bit is not set only when the NSSA ASBR and NSSA ABR are the same router for the area . If bit P = 0, then the NSSA ABR must not translate this LSA into Type 5.

he nssa-only keyword instructs the device to instigate Type-7 LSA with cleared P-bit, thereby, preventing LSA translation to Type 5 on NSSA ABR device.

NotE. If a router is attached to another AS and is also an NSSA ABR, it may originate a both a type-5 and a type-7 LSA for the same network. The type-5 LSA will be flooded to the backbone and the type-7 will be flooded into the NSSA. If this is the case, the P-bit must be reset (P=0) in the type-7 LSA so the type-7 LSA isn’t again translated into a type-5 LSA by another NSSA ABR.

 

---

QUESTION NO: 164

What is the function of an EIGRP sequence TLV packet?

A. to acknowledge a set of sequence numbers during the startup update process
B. to list the peers that should listen to the next multicast packet during the reliable multicast process
C. to list the peers that should not listen to the next multicast packet during the reliable multicast process
D. to define the initial sequence number when bringing up a new peer

 

Answer: C

Explanation:

EIGRP sends updates and other information between routers using multicast packets to 224.0.0.10. For example in the topology below, R1 made a change in the topology and it needs to send updates to R2 & R3. It sends multicast packets to EIGRP multicast address 224.0.0.10. Both R2 & R3 can receive the updates and acknowledge back to R1 using unicast. Simple, right? But what if R1 sends out updates, only R2 replies but R3 never does? In the case a router sends out a multicast packet that must be reliable delivered (like in this case), an EIGRP process will wait until the RTO (retransmission timeout) period has passed before beginning a recovery action. This period is calculated from the SRTT (smooth round-trip time). After R1 sends out updates it will wait for this period to expire. Then it makes a list of all the neighbors from which it did not receive an Acknowledgement (ACK). Next it sends out a packet telling these routers stop listening to multicast until they are been notified that it is safe again. Finally the router will begin sending unicast packets with the information to the routers that didn’t answer, continuing until they are caught up. In our example the process will be like this:

1. R1 sends out updates to 224.0.0.10
2. R2 responds but R3 does not
3. R1 waits for the RTO period to expire
4. R1 then sends out an unreliable-multicast packet, called a sequence TLV (Type Length-Value) packet, which tells R3 not to listen to multicast packets any more
5. R1 continues sending any other muticast traffic it has and delivering all traffic, using unicast to R3, until it acknowledges all the packets
6. Once R3 has caught up, R1 will send another sequence TLV, telling R3 to begin listening to multicast again.
The sequence TLV packet contains a list of the nodes that should not listen to multicast packets while the recovery takes place. But notice that the TLV packet in step 6 does not contain any nodes in the list.
NotE. In the case R3 still does not reply in step 4, R1 will attempt to retransmit the unicast 16 times or continue to retransmit until the hold time for the neighbor in question expires. After this time, R1 will declare a retransmission limit exceeded error and will reset the neighbor.

 

 

---

QUESTION NO: 165

What are two reasons to define static peers in EIGRP? (Choose two.)

A. Security requirements do not allow dynamic learning of neighbors.
B. The link between peers requires multicast packets.
C. Back-level peers require static definition for successful connection.
D. The link between peers requires unicast packets.

 

 

Answer: A,D
Explanation:

There are two ways we can create EIGRP neighbor relationship: + Use “network ” commanD. this is the more popular way to create EIGRP neighbor relationship. That router will check which interfaces whose IP addresses belong to the and turn EIGRP on that interface. EIGRP messages are sent via multicast packets. + Use “neighbor” commanD. The interface(s) that have this command applied no longer send or receive EIGRP multicast packets. EIGRP messages are sent via unicast. The router only accepts EIGRP packets from peers that are explicitly configured with a neighbor statement. Consequently, any messages coming from routers without a corresponding neighbor statement are discarded. This helps prevent the insertion of unauthorized routing peers -> A and D are correct.

 

 

---

QUESTION NO: 166

Refer to the exhibit.

R2 is mutually redistributing between EIGRP and BGP.

Which configuration is necessary to enable R1 to see routes from R3?

A. The R3 configuration must include ebgp-multihop to the neighbor statement for R2.
B. The R2 BGP configuration must include bgp redistribute-internal.
C. R1 must be configured with next-hop-self for the neighbor going to R2.
D. The AS numbers configured on R1 and R2 must match.

 

Answer: B
Explanation:

Whenever you redistribute from BGP to something else, BGP will only advertise externally learned routes. To allow the redistribution of iBGP routes into an interior gateway protocol such as EIGRP or OSPF, use the bgp redistribute-internal command in router configuration mode.

 

 

---

QUESTION NO: 167

What is the purpose of EIGRP summary leaking?

A. to allow a summary to be advertised conditionally on specific criteria
B. to allow a component of a summary to be advertised in addition to the summary
C. to allow overlapping summaries to exist on a single interface
D. to modify the metric of the summary based on which components of the summary are operational

 

Answer: B
Explanation:

When you do manual summarization, and still you want to advertise some specific routes to the neighbor, you can do that using leak-map. Please read more about leaking routes here.

 

 

---

QUESTION NO: 168

Refer to the exhibit.

You have just created a new VRF on PE3. You have enabled debug ip bgp vpnv4 unicast updates on PE1, and you can see the route in the debug, but not in the BGP VPNv4 table. Which two statements are true? (Choose two.)

A. VPNv4 is not configured between PE1 and PE3.
B. address-family ipv4 vrf is not configured on PE3.
C. After you configure route-target import 999:999 for a VRF on PE3, the route will be accepted.
D. PE1 will reject the route due to automatic route filtering.
E. After you configure route-target import 999:999 for a VRF on PE1, the route will be accepted.

 

 

Answer: D,E
Explanation:

The route target extended community for VPLS auto-discovery defines the import and export policies that a VPLS instance uses. The export route target sets an extended community attribute number that is appended to all routes that are exported from the VPLS instance. The import route target value sets a filter that determines the routes that are accepted into the VPLS instance. Any route with a value in its import route target contained in its extended attributes field matching the value in the VPLS instance’s import route target are accepted. Otherwise the route is rejected.

 

 

---

QUESTION NO: 169

Which two DHCP messages are always sent as broadcast? (Choose two.)

A. DHCPOFFER
B. DHCPDECLINE
C. DHCPRELEASE
D. DHCPREQUEST
E. DHCPDISCOVER

 

Answer: D,E

Explanation:

DHCP discovery
The client broadcasts messages DHCPDISCOVER on the network subnet using the destination address 255.255.255.255 or the specific subnet broadcast address.
DHCP request
In response to the DHCP offer, the client replies with a DHCP request, broadcast to the server, requesting the offered address. A client can receive DHCP offers from multiple servers, but it will accept only one DHCP offer.

 

---

QUESTION NO: 170

With which ISs will an ISIS Level 1 IS exchange routing information?

A. Level 1 ISs
B. Level 1 ISs in the same area
C. Level 1 and Level 2 ISs
D. Level 2 ISs

 

 

Answer: B

Explanation:

IS-IS differs from OSPF in the way that "areas" are defined and routed between. IS-IS routers are designated as being: Level 1 (intra-area); Level 2 (inter area); or Level 1-2 (both). Level 2 routers are inter area routers that can only form relationships with other Level 2 routers. Routing information is exchanged between Level 1 routers and other Level 1 routers, and Level 2 routers only exchange information with other Level 2 routers. Level 1-2 routers exchange information with both levels and are used to connect the inter area routers with the intra area routers.

 

---

QUESTION NO: 171

Refer to the exhibit.

Why is the neighbor relationship between R1 & R2 and R1 & R3 an L2-type neighborship?
A. because the area ID on R1 is different as compared to the area ID of R2 and R3
B. because the circuit type on those three routers is L1/L2
C. because the network type between R1, R2, and R3 is point-to-point
D. because the hello interval is not the same on those three routers

 

 

Answer: A

Explanation:

With IS-IS, an individual router is in only one area, and the border between areas is on the link that connects two routers that are in different areas. A Level 2 router may have neighbors in the same or in different areas, and it has a Level 2 link-state database with all information for inter-area routing. Level 2 routers know about other areas but will not have Level 1 information from its own area.

 

---

QUESTION NO: 172

Which three statements about the designated router election in IS-IS are true? (Choose three.)

A. If the IS-IS DR fails, a new DR is elected.
B. The IS-IS DR will preempt. If a new router with better priority is added, it just becomes active in the network.
C. If there is a tie in DR priority, the router with a higher IP address wins.
D. If there is a tie in DR priority, the router with a higher MAC address wins.
E. If the DR fails, the BDR is promoted as the DR.
F. The DR is optional in a point-to-point network.

 

 

Answer: A,B,D
Explanation:

DR/DIS election

Setting priority to 0 doesn't disable DIS election; use point-to-point to disable it.There can be separate DRs for L1 and L2 adjacencies.There is no backup DR. If the primary DR fails, a new DR is elected.DR preemption is enabled by default.

 

---

QUESTION NO: 173

Which three elements compose a network entity title? (Choose three.)

A. area ID
B. domain ID
C. system ID
D. NSAP selector
E. MAC address
F. IP address

 

 

Answer: A,C,D

Explanation:

An IS (Intermediate system) is identified by an address known as a network access point
(NASAP). The NSAP is divided up into three parts as specified by ISO/AI 10589:
Area address—This field is of variable length, composed of high order octets, and it excludes the System ID and N-selector (NSEL) fields. This area address is associated wit a single area within the routing domain.
System ID—This field is 6 octets long and should be set to a unique value with Level 1 and Level
2. The system IS defines an end system (ES) or an IS in an area. You configure the area address and the system ID with the NET command. You can display the system ID with the show isis topology command.
NSEL—This field is called the N-selector, also referred to as the NSAP, and it specifies the upperlayer protocol. The NSEL is the last byte of the NSAP and identifies a network service user. A network service user is a transport entity or the IS network entity itself. When the N-selector is set to zero, the entire NSAP is called a network entity title (NET).
A NET is an NSAP where the last byte is always the n-selector and is always zero. A NET can be from 8 to 20 bytes in length.

 

---

QUESTION NO: 174

Which three statements about IS-IS are true? (Choose three.)

A. IS-IS can be used only in the service provider network.
B. IS-IS can be used to route both IP and CLNP.
C. IS-IS has three different levels of authentication: interface level, process level, and domain level.
D. IS-IS is an IETF standard.
E. IS-IS has the capability to provide address summarization between areas.

 

Answer: B,C,E

Explanation:

Intermediate System to Intermediate System (IS-IS) was designed as the routing protocol for ISO's CLNP described in IS0 10589. IS-IS is a Link State routing protocol akin to OSPF and was developed by DEC for use with DECnet Phase V. It was originally thought that TCP/IP would gradually make way for the seven layer OSI architecture so an enhancement to IS-IS was developed called Integrated IS-IS also known as Dual IS-IS that could route both Connectionless-Mode Network Service (CLNS) as well as IP.
Cisco IOS supports IS-IS authentication on 3 different levels; between neighbors, area-wide, and domain-wide, where each can be used by themselves or together.
summary-address address mask {level-1 | level-1-2 | level-2} is used to configure IP address summarization.

 

---

QUESTION NO: 175

Which statement describes the function of the tracking object created by the track 10 ip route 192.168.99.0/24 reachability command?

A. It tracks the reachability of route 192.168.99.0/24.
B. It tracks the line protocol status of the interface on which route 192.168.99.0/24 is received.
C. It tracks exactly 10 occurrences of route 192.168.99.0/24.
D. It tracks the summary route 192.168.99.0/24 and all routes contained within.

 

 

Answer: A

---

QUESTION NO: 176

Which group of neighbors can be configured as a BGP peer group?

A. a group of iBGP neighbors that have the same outbound route policies
B. a group of iBGP and eBGP neighbors that have the same inbound distribute-list
C. a group of eBGP neighbors in the same autonomous system that have different outbound route policies
D. a group of iBGP neighbors that have different outbound route policies

 

Answer: A

 

---

QUESTION NO: 177

Refer to the exhibit.

Notice that debug ip bgp updates has been enabled. What can you conclude from the debug output?

A. This is the result of the clear ip bgp 10.1.3.4 in command.
B. This is the result of the clear ip bgp 10.1.3.4 out command.
C. BGP neighbor 10.1.3.4 performed a graceful restart.
D. BGP neighbor 10.1.3.4 established a new BGP session.

 

Answer: A
Explanation:

If you enter the clear ip bgp out command for a BGP peer, that router resends its BGP prefixes to that peer. This does not cause a change in the best path on the receiving BGP peer. Hence, there is no change in the Table Version on that peer.

When you run the debug ip bgp updates on the receiving router, you see:
BGP(0): 10.1.3.4 rcvd UPDATE w/ attr: nexthop 10.1.3.4, origin i, metric 0, merged path 4,
AS_PATHBGP(0): 10.1.3.4 rcvd 10.100.1.1/32...duplicate ignored
The received update is recognized as a duplicate, so it is ignored and no best path change occurs.

 

---

QUESTION NO: 178

Which set of commands conditionally advertises 172.16.0.0/24 as long as 10.10.10.10/32 is in the routing table?

A.

B.

C.

D.

 

A. Option A
B. Option B
C. Option C
D. Option D

 

 

Answer: B
Explanation:

Advertise maps are used for conditional routing to advertise specified prefixes if something which is specified in exist map exists. In our question we need to advertise 172.16.0.0/24 if 10.10.10.10/32 exists in the routing table so we have to use commanD. “neighbor x.x.x.x advertise-map <prefix-list of 172.16.0.0/24> exist-map <prefix-list of 10.10.10.10/32>”. Therefore B is correct.

 

---

QUESTION NO: 179

Refer to the exhibit.

Why is R2 unable to ping the loopback interface of R4?

A. The local preference is too high.
B. The weight is too low.
C. The next hop is not reachable from R2.
D. The route originated from within the same AS.

 

Answer: C

Explanation:

Before a BGP speaker installs a route to a network in the main IP routing table, the router must know how to reach the next hop that is used to get to that network. Route reachability is verified by searching for a route to the next hop in the main IP routing table. Unlike IGP routing protocols, such as EIGRP and OSPF, which assume that a route is reachable if they learned it through a valid adjacency, BGP does not install routes that it cannot verify as reachable. If a route to the next hop for a BGP network is found in the main IP routing table, BGP assumes that the network is reachable, and that the particular BGP route might be stored in the main IP routing table. If the router receives a route to a network that is not reachable, that route continues to be stored in the incoming BGP table, adj-RIB-In, and might be seen using the show ip bgp command, but is not placed in the main IP routing table.

 

---

QUESTION NO: 180

Which statement about the BGP originator ID is true?

A. The route reflector always sets the originator ID to its own router ID.
B. The route reflector sets the originator ID to the router ID of the route reflector client that injects the route into the AS.
C. The route reflector client that injects the route into the AS sets the originator ID to its own router ID.
D. The originator ID is set to match the cluster ID.

 

 

Answer: B