All Cisco-Network Study Notes: IP Acclamation Practice

IP Acclamation Practice

Chapter 4, “IP Addressing,” covers abounding capacity accompanying to allegory IP addresses, subnets, and

summarized IP routes. That affiliate suggests some decimal algebraic algorithms that acquiesce you to

find the answers to some archetypal questions afterwards accepting to accomplish timD-consuming

conversions amid bifold and decimal.

As promised in Affiliate 4, this addendum provides some convenance problems that should advice you

perfect the use of the algorithms in Affiliate 4. Note that the ambition of this convenance is not to make

you acquire the algorithms—instead, the ambition is to advice you become so accustomed with the

patterns in the decimal algebraic that you can attending at a botheration and anticipate the acknowledgment quickly.

The absorbed is to accredit you, afterwards you accept accomplished enough, to artlessly attending at a botheration and do

the algebraic in your head, blank the specific accomplish in the book.

This addendum covers the decimal algebraic processes to acknowledgment the afterward four types of

questions:

Given an IP abode and mask/prefix length, account the cardinal of subnets (assuming SLSM),

number of hosts per subnet (assuming SLSM), the subnet number, the advertisement address,

and the ambit of accurate IP addresses in that aforementioned subnet.

Given an IP arrangement and a changeless mask/prefix length, account the subnet numbers.

Given a set of routes, acquisition the aboriginal across-the-board arbitrary route.

Given a set of routes, acquisition the aboriginal absolute arbitrary route(s).

These capacity are covered in adjustment in this appendix. Also, assay http://www.get-cisco-certified.com,

a website at which we intend to action added assay alertness help—we will be abacus additional

practice problems on the web armpit as time permits.

CCIE Routing and Switching Assay Certification Guide

Subnetting Practice

This addendum lists 25 abstracted questions, allurement you to acquire the subnet number, broadcast

address, and ambit of accurate IP addresses. In the solutions, the bifold algebraic is shown, as is the

process that avoids bifold algebraic application the “subnet chart” declared in Affiliate 4, “IP Addressing.”

You ability appetite to assay Affiliate 4’s area on IP acclamation afore aggravating to acknowledgment these

questions.

25 Subnetting Questions

Given anniversary IP abode and mask, accumulation the afterward advice for anniversary of these 25 examples:

■

Size of the arrangement allotment of the address

■

Size of the subnet allotment of the address

■

Size of the host allotment of the address

■

The cardinal of hosts per subnet

■

The cardinal of subnets in this network

■

The subnet number

■

The advertisement address

■

The ambit of accurate IP addresses in this network:

10.180.10.18, affectation 255.192.0.0

10.200.10.18, affectation 255.224.0.0

10.100.18.18, affectation 255.240.0.0

10.100.18.18, affectation 255.248.0.0

10.150.200.200, affectation 255.252.0.0

10.150.200.200, affectation 255.254.0.0

10.220.100.18, affectation 255.255.0.0

10.220.100.18, affectation 255.255.128.0

172.31.100.100, affectation 255.255.192.0

10.

172.31.100.100, affectation 255.255.224.0

11.

172.31.200.10, affectation 255.255.240.0

12.

172.31.200.10, affectation 255.255.248.0

13.

172.31.50.50, affectation 255.255.252.0

IP Acclamation Practice

14.

172.31.50.50, affectation 255.255.254.0

15.

172.31.140.14, affectation 255.255.255.0

16.

172.31.140.14, affectation 255.255.255.128

17.

192.168.15.150, affectation 255.255.255.192

18.

192.168.15.150, affectation 255.255.255.224

19.

192.168.100.100, affectation 255.255.255.240

20.

192.168.100.100, affectation 255.255.255.248

21.

192.168.15.230, affectation 255.255.255.252

22.

10.1.1.1, affectation 255.248.0.0

23.

172.16.1.200, affectation 255.255.240.0

24.

172.16.0.200, affectation 255.255.255.192

25.

10.1.1.1, affectation 255.0.0.0

Suggestions on How to Advance the Problem

If you are accessible to go advanced and alpha answering the questions, go ahead! If you appetite more

explanation of how to advance such questions, accredit aback to the area on IP subnetting in Affiliate 4.

However, if you accept already apprehend Affiliate 4, a admonition of the accomplish in the action to acknowledgment these

questions, with a little bifold math, is again here:

Step 1

Identify the anatomy of the IP address.

Identify the admeasurement of the arrangement allotment of the address, based on Class A, B, and C

rules.

Identify the admeasurement of the host allotment of the address, based on the cardinal of binary

0s in the mask. If the affectation is “tricky,” use the blueprint of archetypal affectation ethics to

convert the affectation to bifold added quickly.

The admeasurement of the subnet allotment is what’s “left over”; mathematically, it is 32 – (network

+ host)

Declare the cardinal of subnets, which is 2

number-of-subnet-bits

– 2.

Declare the cardinal of hosts per subnet, which is 2

number-of-host-bits

– 2

Step 2

Create the subnet blueprint that will be acclimated in accomplish 3 and 4.

Create a all-encompassing subnet chart.

Write bottomward the decimal IP abode and subnet affectation in the aboriginal two rows of the

chart.

NOTE

The examples apparent actuality accept classful IP addressing, so the cardinal of subnets per

IP arrangement is listed as 2

- 2. If application classless IP addressing, the numbers would artlessly be 2

CCIE Routing and Switching Assay Certification Guide

If an accessible affectation is used, draw a vertical band amid the 255s and the 0s in the

mask, from top to basal of the chart. If a adamantine affectation is used, draw a box

around the absorbing octet.

Copy the abode octets to the larboard of the band or the box into the final four rows

of the chart.

Step 3

Derive the subnet cardinal and the aboriginal accurate IP address.

On the band on the blueprint area you are autograph bottomward the subnet number, write

down 0s in the octets to the appropriate of the band or the box.

If the affectation is difficult, so that there is a box in the chart, use the abracadabra number

trick to acquisition the decimal amount of the subnet’s absorbing octet, and abode it

down. Remember, the abracadabra cardinal is activate by adding the interesting

(non-0 or 255) affectation amount from 256. The abracadabra cardinal assorted that’s closest

to but not beyond than the IP address’s absorbing octet amount is the subnet value

in that octet.

To acquire the aboriginal accurate IP address, archetype the aboriginal three octets of the

subnet number, and add 1 to the fourth octet of the subnet number.

Step 4

Derive the advertisement abode and the aftermost accurate IP abode for this subnet.

Write bottomward 255s in the advertisement abode octets to the appropriate of the band or the

box.

If the affectation is difficult, so that there is a box in the chart, use the abracadabra number

trick to acquisition the amount of the advertisement address’s absorbing octet. In this case,

you add the subnet number’s absorbing octet amount to the abracadabra number, and

subtract 1.

To acquire the aftermost accurate IP address, archetype the aboriginal three octets of the broadcast

address and decrease 1 from the fourth octet of the advertisement address.

Question 1: Answer

The answers activate with the assay of the three genitalia of the address, the cardinal of hosts per

subnet, and the cardinal of subnets of this arrangement application the declared mask. The bifold algebraic for

subnet and advertisement abode adding follows. The acknowledgment finishes with the easier mental

calculations application the subnet blueprint declared in Affiliate 4.

Table D-1

Question 1: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Item Example Rules to Remember

Address 10.180.10.18 N/A

Mask 255.192.0.0 N/A

Number of arrangement $.25 8 Always authentic by Class A, B, C

Number of host $.25 22 Always authentic as cardinal of

binary 0s in mask

IP Acclamation Practice

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-2. To

calculate the two numbers, accomplish a Boolean AND on the abode and mask. To acquisition the

broadcast abode for this subnet, change all the host $.25 to bifold 1s in the subnet number. The

host $.25 are in

bold

print in the table.

To get the aboriginal accurate IP address, aloof add 1 to the subnet number; to get the aftermost accurate IP address,

just decrease 1 from the advertisement address. In this case:

10.128.0.1 through 10.191.255.254

10.128.0.0 + 1= 10.128.0.1

10.191.255.255 – 1= 10.191.255.254

Steps 2, 3, and 4 in the action use a table like Table D-3, which lists the way to get the same

answers application the subnet blueprint and abracadabra algebraic declared in Affiliate 4. Figure D-1 at the end of

this botheration shows the fields in Table D-3 that are abounding in at anniversary footfall in the process. Remember,

subtracting the absorbing (non-0 or 255) affectation amount from 256 yields the abracadabra number. The

magic cardinal assorted that’s abutting to but not beyond than the IP address’s absorbing octet value

is the subnet amount in that octet.

Item Example Rules to Remember

Number of subnet $.25 2 32 – (network admeasurement + host size)

Number of subnets 2

– 2 = 2 2

number-of-subnet-bits

– 2

Number of hosts 2

– 2 = 4,194,302 2

number-of-host-bits

– 2

Table D-2

Question 1: Bifold Adding of Subnet and Advertisement Addresses

Address 10.180.10.18 0000 1010 10

11 0100 0000 1010 0001 0010

Mask 255.192.0.0 1111 1111 11

0000 0000 0000 0000 0000

AND result

(subnet number)

10.128.0.0 0000 1010 10

00 0000 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.191.255.255 0000 1010 10

11 1111 1111 1111 1111 1111

Table D-3

Question 1: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet

Chart

Octet 1 Octet 2 Octet 3 Octet 4 Comments

Address 10 180 10 18 N/A

Mask 255 192 0 0 N/A

Subnet cardinal 10 128 0 0 Abracadabra cardinal = 256 – 192 = 64

continues

Table D-1

Question 1: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts (Continued)

CCIE Routing and Switching Assay Certification Guide

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

the abracadabra number, which is 256 – 192 = 64 in this case (256 – mask’s amount in the interesting

octet). The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the

magic cardinal that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this

case, 128 is the assorted of 64 that’s abutting to 180 but not bigger than 180. So, the additional octet

of the subnet cardinal is 128.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Affiliate 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 128 + 64 – 1 = 191.

Finally, Figure D-1 shows Table D-3 with comments about back anniversary allotment of the table was filled

in, based on the accomplish in the action at the alpha of the chapter.

Figure D-1

Steps 2, 3, and 4 for Question 1

Octet 1 Octet 2 Octet 3 Octet 4 Comments

First abode 10 128 0 1 Add 1 to aftermost octet of subnet

Broadcast 10 191 255 255 128 + 64 – 1 = 191

Last abode 10 191 255 254 Decrease 1 from aftermost octet

Subnet rule: Assorted of abracadabra cardinal abutting to, but not added than, IP abode amount in absorbing octet

Broadcast rule: Subnet + abracadabra – 1

Table D-3

Question 1: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet

Chart (Continued)

2C: draw

box

2A:

create

chart

2D: copy

address

Address

Mask

Subnet

number

First

address

Broadcast

Last

address

255

180

192

128 3B

128

191 4B

191

255

255 4A

254 4C

0 3A

1 3C

Magic cardinal = 256

– 192 = 64

Add 1 to aftermost octet

of subnet

128 + 64 – 1 = 191

Subract 1 from

last octet

2B: Abode bottomward address

2B: Abode bottomward mask

Octet

Comments

IP Acclamation Practice

Question 2: Answer

Table D-5 presents the bifold calculations of the subnet cardinal and advertisement address. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in

bold

print in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.192.0.1 through 10.223.255.254

Table D-6 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Affiliate 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

Table D-4

Question 2: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Example Rules to Remember

Address 10.200.10.18 N/A

Mask 255.224.0.0 N/A

Number of arrangement $.25 8 Always authentic by Class A, B, C

Number of host $.25 21 Always authentic as cardinal of bifold 0s

in mask

Number of subnet $.25 3 32 – (network admeasurement + host size)

Number of subnets 2

– 2 = 6 2

number-of-subnet-bits

– 2

Number of hosts 2

– 2 = 2,097,150 2

number-of-host-bits

– 2

Table D-5

Question 2: Bifold Adding of Subnet and Advertisement Addresses

Address 10.200.10.18 0000 1010 110

0 1000 0000 1010 0001 0010

Mask 255.224.0.0 1111 1111 111

0000 0000 0000 0000 0000

AND result

(subnet number)

10.192.0.0 0000 1010 110

0 0000 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.223.255.255 0000 1010 110

1 1111 1111 1111 1111 1111

CCIE Routing and Switching Assay Certification Guide

the abracadabra number, which is 256 – 224 = 32 in this case (256 – mask’s amount in the interesting

octet). The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the

magic cardinal that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this

case, 192 is the assorted of 32 that’s abutting to 200 but not bigger than 200. So, the additional octet

of the subnet cardinal is 192.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Affiliate 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 192 + 32 – 1 = 223.

Question 3: Answer

Table D-6

Question 2: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4 Comments

Address

10 200 10 18 N/A

Mask 255 224 0 0 N/A

Subnet

number

10 192 0 0 Abracadabra cardinal =

256 – 224 = 32

First

address

10 192 0 1 Add 1 to aftermost octet

of subnet

Broadcast 10 223 255 255 192 + 32 – 1 = 223

Last

address

10 223 255 254 Decrease 1 from aftermost octet

Subnet rule: Assorted of abracadabra cardinal abutting to, but not added than, IP abode amount in interesting

octet Advertisement rule: Subnet + abracadabra – 1

Table D-7 Question 3: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Example Rules to Remember

Address 10.100.18.18 N/A

Mask 255.240.0.0 N/A

Number of arrangement $.25 8 Always authentic by Class A, B, C

Number of host $.25 20 Always authentic as cardinal of bifold 0s

in mask

Number of subnet $.25 4 32 – (network admeasurement + host size)

Number of subnets 24 – 2 = 14 2number-of-subnet-bits – 2

Number of hosts 220 – 2 = 1,048,574 2number-of-host-bits – 2

IP Acclamation Convenance 11

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-8. To calculate

the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To acquisition the

broadcast abode for this subnet, change all the host $.25 to bifold 1s in the subnet number. The

host $.25 are in adventurous book in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.96.0.1 through 10.111.255.254

Table D-9 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Affiliate 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

Table D-8 Question 3: Bifold Adding of Subnet and Advertisement Addresses

Address 10.100.18.18 0000 1010 0110 0100 0001 00100001 0010

Mask 255.240.0.0 1111 1111 1111 0000 0000 0000 0000 0000

AND result

(subnet number)

10.96.0.0 0000 1010 0110 0000 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.111.255.255 0000 1010 0110 1111 1111 1111 1111 1111

Table D-9 Question 3: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4 Comments

Address 10 100 18 18 N/A

Mask 255 240 0 0 N/A

Subnet

number

10 96 0 0 Abracadabra number

= 256 – 240 =

First abode 10 96 0 1 Add 1 to last

octet of subnet

Broadcast 10 111 255 255 96 + 16 – 1 =

111

Last abode 10 111 255 254 Decrease 1 from

last octet

Subnet rule: Assorted of abracadabra cardinal abutting to, but not added than, IP abode amount in absorbing octet Broadcast

rule: Subnet + abracadabra – 1

12 CCIE Routing and Switching Assay Certification Guide

the abracadabra number, which is 256 – 240 = 16 in this case (256 – mask’s amount in the interesting

octet). The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the

magic cardinal that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this

case, 96 is the assorted of 16 that’s abutting to 100 but not bigger than 100. So, the additional octet of

the subnet cardinal is 96.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Affiliate 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 96 + 16 – 1 = 111.

Question 4: Answer

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-11. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Table D-10 Question 4: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Example Rules to Remember

Address 10.100.18.18 N/A

Mask 255.248.0.0 N/A

Number of

network bits

8 Always authentic by Class A, B, C

Number of

host bits

19 Always authentic as cardinal of bifold 0s

in mask

Number of

subnet bits

5 32 – (network admeasurement + host size)

Number of

subnets

25 – 2 = 30 2number-of-subnet-bits – 2

Number of

hosts

219 – 2 = 524,286 2number-of-host-bits – 2

Table D-11 Question 4: Bifold Adding of Subnet and Advertisement Addresses

Address 10.100.18.18 0000 1010 0110 0100 0001 00100001 0010

Mask 255.248.0.0 1111 1111 1111 1000 0000 0000 0000 0000

AND result

(subnet number)

10.96.0.0 0000 1010 0110 0000 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.103.255.255 0000 1010 0110 0111 1111 1111 1111 1111

IP Acclamation Convenance 13

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.96.0.1 through 10.103.255.254

Table D-12 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Affiliate 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

the abracadabra number, which is 256 – 248 = 8 in this case (256 – mask’s amount in the absorbing octet).

The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the magic

number that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this case,

96 is the assorted of 8 that’s abutting to 100 but not bigger than 100. So, the additional octet of the

subnet cardinal is 96.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Affiliate 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 96 + 8 – 1 = 103.

Table D-12 Question 4: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4 Comments

Address 10 100 18 18 N/A

Mask 255 248 0 0 N/A

Subnet cardinal 10 96 0 0 Abracadabra number

256 – 248 = 8

First abode 10 96 0 1 Add 1 to last

octet of subnet

Broadcast 10 103 255 255 96 + 8 – 1 =

103

Last abode 10 103 255 254 Decrease 1

from aftermost octet

Subnet rule: Assorted of abracadabra cardinal abutting to, but not added than, IP abode amount in absorbing octet

Broadcast rule: Subnet + abracadabra – 1

14 CCIE Routing and Switching Exam Certification Guide

Question 5: Answer

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-14. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.148.0.1 through 10.151.255.254

Table D-15 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Chapter 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

Table D-13 Question 5: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Archetype Rules to Remember

Address 10.150.200.200 N/A

Mask 255.252.0.0 N/A

Number of

network bits

8 Always authentic by Class A, B, C

Number of

host bits

18 Always authentic as cardinal of binary

0s in mask

Number of

subnet bits

6 32 – (network admeasurement + host size)

Number of

subnets

26 – 2 = 62 2number-of-subnet-bits – 2

Number of hosts 218 – 2 = 262,142 2number-of-host-bits – 2

Table D-14 Question 5: Bifold Calculation of Subnet and Advertisement Addresses

Address 10.150.200.200 0000 1010 1001 0110 1100 1000 1100 1000

Mask 255.252.0.0 1111 1111 1111 1100 0000 0000 0000 0000

AND result

(subnet number)

10.148.0.0 0000 1010 0110 0100 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.151.255.255 0000 1010 0110 0111 1111 1111 1111 1111

IP Addressing Practice 15

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

the abracadabra number, which is 256 – 252 = 4 in this case (256 – mask’s amount in the absorbing octet).

The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the magic

number that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this case,

148 is the assorted of 4 that’s abutting to 150 but not bigger than 150. So, the additional octet of the

subnet cardinal is 148.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Chapter 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 148 + 4 – 1 = 151.

Question 6: Answer

Table D-15 Question 5: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4 Comments

Address 10 150 200 200 N/A

Mask 255 252 0 0 N/A

Subnet

number

10 148 0 0 Magic

number =

256 – 252 = 4

First abode 10 148 0 1 Add 1 to last

octet of

subnet

Broadcast 10 151 255 255 148 + 4 – 1 =

151

Last abode 10 151 255 254 Decrease 1

from last

octet

Subnet rule: Assorted of abracadabra cardinal abutting to, but not added than, IP abode amount in absorbing octet

Broadcast rule: Subnet + abracadabra – 1

Table D-16 Question 6: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Archetype Rules to Remember

Address 10.150.200.200 N/A

Mask 255.254.0.0 N/A

Number of

network bits

8 Always authentic by Class A, B, C

continues

16 CCIE Routing and Switching Exam Certification Guide

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-17. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.150.0.1 through 10.151.255.254

Table D-18 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Chapter 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

Step Archetype Rules to Remember

Number of

host bits

17 Always authentic as cardinal of binary

0s in mask

Number of

subnet bits

7 32 – (network admeasurement + host size)

Number of

subnets

27 – 2 = 126 2number-of-subnet-bits – 2

Number of

hosts

217 – 2 = 131,070 2number-of-host-bits – 2

Table D-17 Question 6: Bifold Calculation of Subnet and Advertisement Addresses

Address 10.150.200.200 0000 1010 1001 0110 1100 1000 1100 1000

Mask 255.254.0.0 1111 1111 1111 1110 0000 0000 0000 0000

AND result

(subnet number)

10.150.0.0 0000 1010 0110 0110 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.151.255.255 0000 1010 0110 0111 1111 1111 1111 1111

Table D-18 Question 6: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet

Chart

Octet 1 Octet 2 Octet 3 Octet 4

Address 10 150 200 200

Mask 255 254 0 0

Table D-16 Question 6: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts (Continued)

IP Addressing Practice 17

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The second

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

the abracadabra number, which is 256 – 254 = 2 in this case (256 – mask’s amount in the absorbing octet).

The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the magic

number that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this case,

150 is the assorted of 2 that’s abutting to 150 but not bigger than 150. So, the additional octet of the

subnet cardinal is 150.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Chapter 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 150 + 2 – 1 = 151.

Question 7: Answer

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-20. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Octet 1 Octet 2 Octet 3 Octet 4

Subnet cardinal 10 150 0 0

First valid

address

10 150 0 1

Broadcast 10 151 255 255

Last valid

address

10 151 255 254

Table D-19 Question 7: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Archetype Rules to Remember

Address 10.220.100.18 N/A

Mask 255.255.0.0 N/A

Number of arrangement $.25 8 Always authentic by Class A, B, C

Number of host $.25 16 Always authentic as cardinal of bifold 0s in

mask

Number of subnet $.25 8 32 – (network admeasurement + host size)

Number of subnets 28 – 2 = 254 2number-of-subnet-bits – 2

Number of hosts 216 – 2 = 65,534 2number-of-host-bits – 2

Table D-18 Question 6: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet

Chart (Continued)

18 CCIE Routing and Switching Exam Certification Guide

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.220.0.1 through 10.220.255.254

Table D-21 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Chapter 4.

This subnetting arrangement uses an accessible affectation because all of the octets are a 0 or a 255. No algebraic tricks

are bare at all!

Question 8: Answer

Table D-20 Question 7: Bifold Calculation of Subnet and Advertisement Addresses

Address 10.220.100.18 0000 1010 1101 1100 0110 0100 0001 0010

Mask 255.255.0.0 1111 1111 1111 1111 0000 0000 0000 0000

AND result

(subnet number)

10.220.0.0 0000 1010 1101 1100 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.220.255.255 0000 1010 1101 1100 1111 1111 1111 1111

Table D-21 Question 7: Subnet, Broadcast, First, and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4

Address 10 220 100 18

Mask 255 255 0 0

Subnet cardinal 10 220 0 0

First valid

address

10 220 0 1

Broadcast 10 220 255 255

Last valid

address

10 220 255 254

Table D-22 Question 8: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Archetype Rules to Remember

Address 10.220.100.18 N/A

Mask 255.255.128.0 N/A

Number of arrangement $.25 8 Always authentic by Class A, B, C

IP Addressing Practice 19

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-23. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

10.220.0.1 through 10.220.127.254

Table D-24 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described

in Chapter 4. Remember, adding the absorbing (non-0 or 255) affectation amount from 256 yields

the abracadabra number. The abracadabra cardinal assorted that’s abutting to but not beyond than the IP address’s

interesting octet amount is the subnet amount in that octet.

Step Archetype Rules to Remember

Number of host $.25 15 Always authentic as cardinal of bifold 0s in

mask

Number of subnet $.25 9 32 – (network admeasurement + host size)

Number of subnets 29 – 2 = 510 2number-of-subnet-bits – 2

Number of hosts 215 – 2 = 32,766 2number-of-host-bits – 2

Table D-23 Question 8: Bifold Calculation of Subnet and Advertisement Addresses

Address 10.220.100.18 0000 1010 1101 1100 0110 0100 0001 0010

Mask 255.255.128.0 1111 1111 1111 1111 1000 0000 0000 0000

AND aftereffect (subnet

number)

10.220.0.0 0000 1010 1101 1100 0000 0000 0000 0000

Change host to 1s

(broadcast address)

10.220.127.255 0000 1010 1101 1100 0111 1111 1111 1111

Table D-24 Question 8: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Octet 1 Octet 2 Octet 3 Octet 4

Address 10 220 100 18

Mask 255 255 128 0

Subnet cardinal 10 220 0 0

First abode 10 220 0 1

Broadcast 10 220 127 255

Last Adress 10 220 127 254

Table D-22 Question 8: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts (Continued)

20 CCIE Routing and Switching Exam Certification Guide

This subnetting arrangement uses a adamantine affectation because one of the octets is not a 0 or a 255. The third

octet is “interesting” in this case. The key allotment of the ambush to get the appropriate answers is to calculate

the abracadabra number, which is 256 – 128 = 128 in this case (256 – mask’s amount in the interesting

octet). The subnet number’s amount in the absorbing octet (inside the box) is the assorted of the

magic cardinal that’s not bigger than the aboriginal IP address’s amount in the absorbing octet. In this

case, 0 is the assorted of 128 that’s abutting to 100 but not bigger than 100. So, the third octet of the

subnet cardinal is 0.

The additional catchy allotment of this action calculates the subnet advertisement address. The abounding action is

described in Chapter 4, but the catchy allotment is, as usual, in the “interesting” octet. Take the subnet

number’s amount in the absorbing octet, add the abracadabra number, and decrease 1. That’s the broadcast

address’s amount in the absorbing octet. In this case, 0 + 128 – 1 = 127.

This archetype tends to abash bodies because a affectation with 128 in it gives you subnet numbers that

just do not assume to attending right. Table D-25 gives you the answers for the aboriginal several subnets, just

to accomplish abiding that you are bright about the subnets back application this affectation with a Class A network.

Question 9: Answer

Table D-25 Question 8: Subnet, Broadcast, Aboriginal and Aftermost Addresses Calculated Application Subnet Chart

Zero Subnet

First Valid

Subnet

Second Valid

Subnet

Third Valid

Subnet

Subnet 10.0.0.0 10.0.128.0 10.1.0.0 10.1.128.0

First abode 10.0.0.1 10.0.128.1 10.1.0.1 10.1.128.1

Last abode 10.0.127.254 10.0.255.254 10.1.127.254 10.1.255.254

Broadcast 10.0.127.255 10.0.255.255 10.1.127.255 10.1.255.255

Table D-26 Question 9: Admeasurement of Network, Subnet, Host, Cardinal of Subnets, Cardinal of Hosts

Step Archetype Rules to Remember

Address 172.31.100.100 N/A

Mask 255.255.192.0 N/A

Number of arrangement $.25 16 Always authentic by

Class A, B, C

Number of host $.25 14 Always authentic as cardinal of

binary 0s in mask

Number of subnet $.25 2 32 – (network admeasurement + host size)

Number of subnets 22 – 2 = 2 2number-of-subnet-bits – 2

Number of hosts 214 – 2 = 16,382 2number-of-host-bits – 2

IP Addressing Practice 21

The bifold calculations of the subnet cardinal and advertisement abode are in Table D-27. To

calculate the subnet number, accomplish a Boolean AND of the abode with the subnet mask. To find

the advertisement abode for this subnet, change all the host $.25 to bifold 1s in the subnet number.

The host $.25 are in adventurous book in the table.

Just add 1 to the subnet cardinal to get the aboriginal accurate IP address; aloof decrease 1 from the broadcast

address to get the aftermost accurate IP address. In this case:

172.31.64.1 through 172.31.127.254

Table D-28 lists the way to get the aforementioned answers application the subnet blueprint and abracadabra algebraic described