Refer to the exhibit. Which configuration is required to summarize the Area 2 networks that are advertised to Area 0?
Refer to the exhibit. Which configuration is required to summarize the Area 2 networks that are advertised to Area 0?
To summarize the Area 2 networks that are advertised to Area 0, you need to create a summary address that aggregates the three /24 subnets: 192.168.36.0/24, 192.168.37.0/24, and 192.168.38.0/24. The appropriate summary address for these networks is 192.168.36.0 with a subnet mask of 255.255.252.0 (/22), which covers the entire range from 192.168.36.0 to 192.168.39.255. Configuring the command 'area 2 range 192.168.36.0 255.255.252.0' on Router B achieves this summary.
This is really a subnetting question. Nothing really to do with OSPF if you think about what the question is asking you. It wants you to summarize 3 /24s B only covers one /24.. what about the other two networks? WRONG C is getting somewhere with a /22 but the wrong network ID is listed. 38.0 in a /22 is a client IP, not a network IP D is like B, it only covers the first /24 and not the entire /22 we need to include all 3 /24s A is the only answer that works. in a /22, 192.168.36.0 is a network IP that covers up to 192.168.39.255
its always area you are summarizing from. In this case we are summerzing area 2 routes and check aggregated (Supernet) Mask.
this is ABR (area 0 & 22) : cisco_R3(config-router)#area 22 range 55.0.0.0 255.255.192.0 cisco_R3(config-router)# cisco_R3(config-router)#do s runn | s router ospf router ospf 1 router-id 3.3.3.3 auto-cost reference-bandwidth 1000 area 22 range 55.0.0.0 255.255.192.0 area 22 filter-list prefix PL_3 in passive-interface default no passive-interface Ethernet0/0.10 no passive-interface Ethernet0/0.50 network 0.0.0.0 255.255.255.255 area 0 bfd all-interfaces cisco_R3(config-router)#
far-end in the area 0 - netw mask has been changed + debug; cisco_R2#show ip route ospf 55.0.0.0/24 is subnetted, 1 subnets O IA 55.0.0.0 [110/201] via 192.168.255.3, 00:07:30, Ethernet0/0.10 cisco_R2# cisco_R2# *Dec 23 15:27:11.674: RT: updating ospf 55.0.0.0/18 (0x0) : via 192.168.255.3 Et0/0.10 0 1048578 *Dec 23 15:27:11.674: RT: network 55.0.0.0 is now variably masked *Dec 23 15:27:11.674: RT: add 55.0.0.0/18 via 192.168.255.3, ospf metric [110/201] *Dec 23 15:27:11.674: RT: updating ospf 10.111.10.0/30 (0x0) : via 192.168.255.3 Et0/0.10 0 1048578 *Dec 23 15:27:11.674: RT: rib update return code: 17 *Dec 23 15:27:11.679: RT: del 55.0.0.0 via 192.168.255.3, ospf metric [110/201] *Dec 23 15:27:11.679: RT: delete subnet route to 55.0.0.0/24 cisco_R2# cisco_R2#show ip route ospf 55.0.0.0/18 is subnetted, 1 subnets O IA 55.0.0.0 [110/201] via 192.168.255.3, 00:02:09, Ethernet0/0.10 cisco_R2#
+ you'll see this summary route on the ABR, it will reject all traffic that does not match more specific route in this range (everything in range 55.0.0.0/18 -> Null0 except 55.0.0.0/24 ) cisco_R3#show ip route ospf | b Ga Gateway of last resort is 2.2.2.2 to network 0.0.0.0 55.0.0.0/8 is variably subnetted, 2 subnets, 2 masks O 55.0.0.0/18 is a summary, 00:07:13, Null0 <<<<<<<<<<<<<<<<<<< reject O 55.0.0.0/24 [110/101] via 10.111.10.2, 00:07:13, Ethernet0/0.50 <<<<<<<<< except this cisco_R3#
Provided answer is correct.
How many hosts in each network? /24 = 255 hosts How many networks do we have to summarize them? 3 (192.168.36.0 - 192.168.37.0 - 192.168.38.0). Let's multiply: 255 x 3 = 765 What is the closest prefix that contains 765 host? /23 255.255.255.252 The answer is 192.168.36.0 255.255.252.0 A is correct.
* What is the closest prefix that contains 765 host? /23 255.255.252.0
It should be /22 not 23, sorry again
A is correct