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- CCNA Routing and Switching 200-105
61.
An enterprise router (R1) has a working eBGP peer relationship with ISP router R2.
Both routers use the default setting of no auto-summary. Examine the following output from R1. Based on that output, which of the following answers, when added to
R1’s BGP configuration, causes R1 to advertise a BGP route to Router R2?
R1# show ip route 200.1.1.0 255.255.255.0 longer-prefixes 200.1.1.0/24 is variably subnetted, 3 subnets, 3 masks C 200.1.1.0/27 is directly connected, Loopback1 L 200.1.1.1/32 is directly connected, Loopback1 O 200.1.1.32/28 [110/2] via 10.1.1.1, 03:11:00, GigabitEthernet0/2
- A.network 200.1.1.0 mask 255.255.255.0
- B.network 200.1.1.0
- C.network 200.1.1.0 mask 255.255.255.240
- D.None of the other answers causes R1 to advertise a route to R2.
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
|
To cause the injection of a route from the IP routing table to the BGP table,
the network command must match a route in the IP routing table, unless the
auto-summary command has also been added to the configuration. One answer lists
prefix 200.1.1.0, but mask 255.255.255.0, and both must match the IP route—and
the mask does not match. Likewise, the command with subnet 200.1.1.0 and mask
255.255.255.240 does not match any of the routes, either. The network 200.1.1.0
command implies the default mask—a Class C default mask of 255.255.255.0 in this
case—and again does not match any of the routes in the routing table. Note that the commands that would match routes in this router’s routing table include network 200.1.1.0 mask 255.255.255.224, which matches connected subnet 200.1.1.0/27, and network 200.1.1.32 mask 255.255.255.240, which matches the one OSPF-learned route. |
62.
Examine the output. Which of the following statements are true based on the output
of this show command from Router R1? (Choose two answers.)
R1# show ip bgp summary BGP router identifier 2.2.2.2, local AS number 101 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 1.1.1.1 4 201 2 2 1 0 0 00:00:37 1
- A.Neighbor 1.1.1.1 is an eBGP peer.
- B.The TCP connection needed by BGP is not working at this point.
- C.R1 has sent one prefi x to neighbor 1.1.1.1.
- D.R1 has a neighbor 1.1.1.1 remote-as 201 command configured.
- Answer & Explanation
- Report
Answer : [A and D]
Explanation :
Explanation :
|
The one BGP peer listed on R1, 1.1.1.1, is an eBGP peer. The line that lists
1.1.1.1 also lists the peer’s ASN (201). The first line of output lists R1’s ASN (101), so
with different ASNs, the peer is an eBGP peer. The line that lists the peer (1.1.1.1) basically relists the information in the neighbor 1.1.1.1 remote-as 201 command in two of the first three items in that line. The state of this peer is established, which is the final BGP state, after the TCP connection is established and the BGP peers have agreed that their parameters match and they can exchange routes. The state is known by virtue of a number being listed on the far right in the “State/PfxRcd” column. That same column lists 1, meaning R1 has received or learned one prefix from this peer—not that R1 has sent one prefix to this peer. |
63.
In the cabling for a leased line, which of the following usually connects to a four-wire
line provided by a telco?
- A.Router serial interface without internal CSU/DSU
- B.CSU/DSU
- C.Router serial interface with internal transceiver.
- D.Switch serial interface
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The four-wire circuit cable supplied by the telco connects to the device acting as the CSU/DSU. That can be an external CSU/DSU or a CSU/DSU integrated into a router serial interface card. LAN switches do not have serial interfaces, and router serial interfaces do not have transceivers. |
64.
Two routers connect with a serial link, each using its S0/0/0 interface. The link is
currently working using PPP. The network engineer wants to migrate to use the
Cisco-proprietary HDLC that includes a protocol type field. Which of the following
commands can be used to migrate to HDLC successfully? (Choose two answers.)
- A.encapsulation hdlc
- B.encapsulation cisco-hdlc
- C.no encapsulation ppp
- D.encapsulation-type auto
- Answer & Explanation
- Report
Answer : [A and C]
Explanation :
Explanation :
| The encapsulation hdlc command sets the interface encapsulation (datalink protocol) to HDLC. In addition, because Cisco routers default to use the Cisco-proprietary HDLC on serial interfaces, removing the use of PPP with the no encapsulation ppp command also works. The other two answers list commands that do not exist in IOS. |
65.
Which of the following PPP authentication protocols authenticates a device on the
other end of a link without sending any password information in clear text?
- A.MD5
- B.PAP
- C.CHAP
- D.DES
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Of the possible answers, only PAP and CHAP are PPP authentication protocols. PAP sends the password as clear text between the two devices. |
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