Odom's Chapter 21 answers do not make sense
binaryhat
Member Posts: 129
in CCNA & CCENT
Problem I: Best Summarized Route
Address
Mask
Block Size
Subnet
Broadcast
10.1.50..0/23
/22
2^2=4
10.1.46.0
10.1.49.255
10.1.48.0/23
/21
2^3=8
10.1.46.0
10.1.53.255
10.1.46.0/23
/20
2^4=16
10.1.46.0
10.1.61.255
10.1.52.0/23
/19
2^5=32
10.1.46.0
10.1.77.255
Problem II: Best Summarized Route
Address
Mask
Block Size
Subnet
Broadcast
172.16.112.0/24
/22
4
172.16.111.0
172.16.114.255
172.16.114.0/25
/21
8
172.16.111.0
172.16.118.255
172.16.116.0/23
/20
16
172.16.111.0
172.16.126.255
172.16.111.0/24
/19
32
172.16.111.0
172.16.132.255
Problem III: Best Summarized Route
Address
Mask
Block Size
Subnet
Broadcast
192.1.168.1.160/28
/27
32
192.168.1.128
192.1.168.1.159
192.1.168.1.152/30
/26
64
192.168.1.128
192.1.168.1.191
192.1.168.1.192/29
/25
128
192.168.1.128
192.1.168.1.255
192.1.168.1.128/28
/24
256
192.168.1.128
na
Problem IV: Best Summarized Route
Address
Mask
Block Size
Subnet
Broadcast
172.16.125.0/24
/23
2
172.16.125.0
172.16.126.255
172.16.126.0/24
/22
4
172.16.125.0
172.16.128.255
172.16.127.0/24
/21
8
172.16.125.0
172.16.132.255
172.16.128.0/24
/20
16
172.16.125.0
172.16.140.255
My answers are in red. His answers do not make sense to me based on his explanation or lack there of. It's Chapter 21 pages 571-573. His explanation for finding the best summarized route is:
Currently working on:
ICND1 - TBD
Book: CCENT/CCNA ICND1 100-101 Official Cert Guide
Equipment: Packet Tracer, GNS3
Supplement Material: Youtube, Google, Boson ExamSim-Max, CBTNuggets
ICND1 - TBD
Book: CCENT/CCNA ICND1 100-101 Official Cert Guide
Equipment: Packet Tracer, GNS3
Supplement Material: Youtube, Google, Boson ExamSim-Max, CBTNuggets
Comments
-
xnx
Member Posts: 464 ■■■□□□□□□□
With route summaries you want to find the lowest IP address in the range for e.g 10.1.0.0 and then the highest e.g 10.1.7.0.
Now you want to find a mask that will increment from your lower range and cover your highest range, this will be a multiple of 2, in this case 8.
Now you want to increment from 0 to 8 in 3rd octet, /21 - 255.255.248.0 (goes up in 8's in 3rd octet)
Summary will be 10.1.0.0 / 21.
Note: it's nearly 4am here so I can't explain it any better at the momentGetting There ...
Lab Equipment: Using Cisco CSRs and 4 Switches currently -
binaryhat
Member Posts: 129
UpdatedProblem I: Best Summarized RouteAddressMaskBlock SizeSubnetBroadcast10.1.50..0/23/222^2=410.1.44.010.1.47.25510.1.48.0/23/212^3=810.1.40.010.1.47.25510.1.46.0/23/202^4=1610.1.32.010.1.47.25510.1.52.0/23/192^5=3210.1.32.010.1.63.25510.1.46.0 is a host address, not divisible by 4Problem II: Best Summarized RouteAddressMaskBlock SizeSubnetBroadcast172.16.112.0/24/224172.16.108.0172.16.111.255172.16.114.0/25/218172.16.104.0172.16.111.255172.16.116.0/23/2016172.16.96.0172.16.111.255172.16.111.0/24/1932172.16.96.0172.16.127.255***Start with block size and see if address is divisible by itProblem III: Best Summarized RouteAddressMaskBlock SizeSubnetBroadcast192.1.168.1.160/28/2732192.1.168.128192.1.168.1.159192.1.168.1.152/30/2664192.1.168.128192.1.168.1.191192.1.168.1.192/29/25128192.1.168.128192.1.168.1.255192.1.168.1.128/28/24256192.1.168.128naProblem IV: Best Summarized RouteAddressMaskBlock SizeSubnetBroadcast172.16.125.0/24/232172.16.124.0172.16.125.255172.16.126.0/24/224172.16.124.0172.16.127.255172.16.127.0/24/218172.16.120.0172.16.127.255172.16.128.0/24/2016172.16.112.0172.16.127.255/1932172.16.96.0172.16.127.255/1864172.16.64.0172.16.127.255/17128172.16.0.0172.16.127.255/16255172.16.0.0172.16.255.255Currently working on:
ICND1 - TBD
Book: CCENT/CCNA ICND1 100-101 Official Cert Guide
Equipment: Packet Tracer, GNS3
Supplement Material: Youtube, Google, Boson ExamSim-Max, CBTNuggets