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CCNA - Subnetting (IPv4) > Classless Addressing (CIDR) > Flashcards

Classless Addressing (CIDR) Flashcards

1
Q

What does the abbreviation CIDR stand for?

A

Classless Inter-Domain Routing

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2
Q

What is the equation for calculating the number of bits to borrow for subnetting (Priority is on the number of networks)?

A

Number of network = 2**n

where “n” is the number of bits to borrow

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3
Q

What is the equation for calculating the number of bits to borrow for subnetting (Priority is on the number of hosts per network)?

A

Number of host = (2**n) - 2
where “n” is the number of bits to use for the host portion.
Once you know the “n”, then calculate number of bits to borrow as below:
For Class A = 24 - n
For Class B = 16 - n
For Class C = 8 - n

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4
Q

For a Class C network, if we borrowed one (1) bit, how many subnets will you have?

A

2

Given all zero network is permitted

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5
Q

For a Class C network, if we borrowed two (2) bits, how many subnets will you have?

A

4

Calculation: 2**2 = 4

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6
Q

For a Class C network, if we borrowed three (3) bits, how many subnets will you have?

A

8

Calculation: 2**3 = 8

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7
Q

For a Class C network, if we borrowed four (4) bits, how many subnets will you have?

A

16

Calculation: 2**4 = 16

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8
Q

For a Class C network, if we borrowed five (5) bits, how many subnets will you have?

A

32

Calculation: 2**5 = 32

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9
Q

For a Class C network, if we borrowed six (6) bits, how many subnets will you have?

A

64

Calculation: 2**6 = 64

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10
Q

For a Class C network, if we borrowed seven (7) bit, how many subnets will you have?

A

Invalid borrowing since this only leaves one (1) bit for the host portion.

Explanation:

  1. All zeroes on the host portion means it is a network address
  2. All ones on the host portion means it is a broadcast address
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11
Q

For a Class C network, if we borrowed eight (8) bits, how many subnets will you have?

A

Invalid borrowing since this leaves no bits for the host portion.

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12
Q

For a Class C network, if we borrowed one (1) bit for subnet, how many hosts will you have?

A

126
Calculation: Borrowed 1 bit, so 7 bits left for host.
2**7 - 2 = 128 - 2 = 126

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13
Q

For a Class C network, if we borrowed two (2) bits for subnet, how many hosts will you have?

A

62
Calculation: Borrowed 2 bits, so 6 bits left for host.
2**6 - 2 = 64 - 2 = 62

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14
Q

For a Class C network, if we borrowed three (3) bits for subnet, how many hosts will you have?

A

30
Calculation: Borrowed 3 bits, so 5 bits left for host.
2**5 - 2 = 32 - 2 = 30

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15
Q

For a Class C network, if we borrowed four (4) bits for subnet, how many hosts will you have?

A

14
Calculation: Borrowed 4 bits, so 4 bits left for host.
2**4 - 2 = 16 - 2 = 14

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16
Q

For a Class C network, if we borrowed five (5) bits for subnet, how many hosts will you have?

A

6
Calculation: Borrowed 5 bits, so 3 bits left for host.
2**3 - 2 = 6 - 2 = 6

17
Q

For a Class C network, if we borrowed six (6) bits for subnet, how many hosts will you have?

A

2
Calculation: Borrowed 6 bits, so 2 bits left for host.
2**2 - 2 = 4 - 2 = 2

18
Q

For a Class C network, if we borrowed seven (7) bits for subnet, how many hosts will you have?

A

Not a valid option for subnet.
Calculation: Borrowed 7 bits, so 1 bit left for host.
2**1 - 2 = 2 - 0 = 0

19
Q

For a Class C network, if we borrowed one (1) bit, what is the “magic” number you add to list all the subnetworks?

A

128
Calculation: Borrowed 1 bit for subnet.
The bits would look like nhhh hhhh (n=network, h=host).
The last n is in the 8th position which has the decimal value of 128.
To make a list of all the subnets, simply start to add 128 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the “zero” network)
2nd network: 192.168.1.128 (add 128)

20
Q

For a Class C network, if we borrowed two (2) bits, what is the “magic” number you add to list all the subnetworks?

A

64
Calculation: Borrowed 2 bits for subnet.
The bits would look like nnhh hhhh (n=network, h=host).
The last n is in the 7th position which has the decimal value of 64.
To make a list of all the subnets, simply start to add 64 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the “zero” network)
2nd network: 192.168.1.64 (add 64)
3rd network: 192.168.1.128 (add 64)
4th network: 192.168.1.192 (add 64)

21
Q

For a Class C network, if we borrowed three (3) bits, what is the “magic” number you add to list all the subnetworks?

A

32
Calculation: Borrowed 3 bits for subnet.
The bits would look like nnnh hhhh (n=network, h=host).
The last n is in the 6th position which has the decimal value of 32.
To make a list of all the subnets, simply start to add 32 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the “zero” network)
2nd network: 192.168.1.32 (add 32)
3rd network: 192.168.1.64 (add 32)
4th network: 192.168.1.96 (add 32)
5th network: 192.168.1.128 (add 32)
6th network: 192.168.1.160 (add 32)
7th network: 192.168.1.192 (add 32)
8th network: 192.168.1.224 (add 32)

22
Q

For a Class C network, if we borrowed four (4) bits, what is the “magic” number you add to list all the subnetworks?

A 
16
Calculation: Borrowed 4 bits for subnet. 
The bits would look like nnnn hhhh (n=network, h=host).
The last n is in the 5th position which has the decimal value of 16.
To make a list of all the subnets, simply start to add 16 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the "zero" network)
2nd network: 192.168.1.16 (add 16) 
3rd network: 192.168.1.32 (add 16)
4th network: 192.168.1.48 (add 16)
5th network: 192.168.1.64 (add 16)
6th network: 192.168.1.80 (add 16)
7th network: 192.168.1.96 (add 16)
8th network: 192.168.1.112 (add 16)
9th network: 192.168.1.128 (add 16)
10th network: 192.168.1.144 (add 16)
11th network: 192.168.1.160 (add 16)
12th network: 192.168.1.176 (add 16)
13th network: 192.168.1.192 (add 16)
14th network: 192.168.1.208 (add 16)
15th network: 192.168.1.224 (add 16)
16th network: 192.168.1.240 (add 16)
23
Q

For a Class C network, if we borrowed five (5) bits, what is the “magic” number you add to list all the subnetworks?

A 
8
Calculation: Borrowed 5 bits for subnet. 
The bits would look like nnnn nhhh (n=network, h=host).
The last n is in the 4th position which has the decimal value of 8.
To make a list of all the subnets, simply start to add 8 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the "zero" network)
2nd network: 192.168.1.8 (add 8) 
3rd network: 192.168.1.16 (add 8)
4th network: 192.168.1.24 (add 8)
5th network: 192.168.1.32 (add 8)
6th network: 192.168.1.40 (add 8)
7th network: 192.168.1.48 (add 8)
8th network: 192.168.1.56 (add 8)
9th network: 192.168.1.64 (add 8)
10th network: 192.168.1.72 (add 8)
11th network: 192.168.1.80 (add 8)
12th network: 192.168.1.88 (add 8)
13th network: 192.168.1.96 (add 8)
14th network: 192.168.1.104 (add 8)
15th network: 192.168.1.112 (add 8)
16th network: 192.168.1.120 (add 8)
17th network: 192.168.1.128 (add 8)
18th network: 192.168.1.136 (add 8)
19th network: 192.168.1.144 (add 8)
20th network: 192.168.1.152 (add 8)
21th network: 192.168.1.160 (add 8)
22nd network: 192.168.1.168 (add 8)
23rd network: 192.168.1.176 (add 8)
24rd network: 192.168.1.184 (add 8)
25th network: 192.168.1.192 (add 8)
26th network: 192.168.1.200 (add 8)
27th network: 192.168.1.208 (add 8)
28th network: 192.168.1.226 (add 8)
29th network: 192.168.1.224 (add 8)
30th network: 192.168.1.232 (add 8)
31st network: 192.168.1.240 (add 8)
32nd network: 192.168.1.248 (add 8)
24
Q

For a Class C network, if we borrowed six (6) bits, what is the “magic” number you add to list all the subnetworks?

A 
4
Calculation: Borrowed 6 bits for subnet. 
The bits would look like nnnn nnhh (n=network, h=host).
The last n is in the 3rd position which has the decimal value of 4.
To make a list of all the subnets, simply start to add 4 to the network address before it.
Example:
Subnet 192.168.1.0
1st network: 192.168.1.0 (the "zero" network)
2nd network: 192.168.1.4 (add 4) 
3rd network: 192.168.1.8 (add 4)
4th network: 192.168.1.12 (add 4)
5th network: 192.168.1.16 (add 4)
6th network: 192.168.1.20 (add 4)
7th network: 192.168.1.24 (add 4)
8th network: 192.168.1.28 (add 4)
9th network: 192.168.1.32 (add 4)
10th network: 192.168.1.36 (add 4)
11th network: 192.168.1.40 (add 4)
12th network: 192.168.1.44 (add 4)
13th network: 192.168.1.48 (add 4)
14th network: 192.168.1.52 (add 4)
15th network: 192.168.1.56 (add 4)
16th network: 192.168.1.60 (add 4)
17th network: 192.168.1.64 (add 4)
18th network: 192.168.1.68 (add 4)
19th network: 192.168.1.72 (add 4)
20th network: 192.168.1.76 (add 4)
21th network: 192.168.1.80 (add 4)
22nd network: 192.168.1.84 (add 4)
23rd network: 192.168.1.88 (add 4)
24rd network: 192.168.1.92 (add 4)
25th network: 192.168.1.96 (add 4)
26th network: 192.168.1.100 (add 4)
27th network: 192.168.1.104 (add 4)
28th network: 192.168.1.108 (add 4)
29th network: 192.168.1.112 (add 4)
30th network: 192.168.1.116 (add 4)
31st network: 192.168.1.120 (add 4)
32nd network: 192.168.1.124 (add 4)
33rd network: 192.168.1.128 (add 4)
34th network: 192.168.1.132 (add 4)
35th network: 192.168.1.136 (add 4)
36th network: 192.168.1.140 (add 4)
37nd network: 192.168.1.144 (add 4)
38th network: 192.168.1.148 (add 4)
39th network: 192.168.1.152 (add 4)
40th network: 192.168.1.156 (add 4)
41st network: 192.168.1.160 (add 4)
42nd network: 192.168.1.164 (add 4)
43rd network: 192.168.1.168 (add 4)
44th network: 192.168.1.172 (add 4)
45th network: 192.168.1.176 (add 4)
46th network: 192.168.1.180 (add 4)
47th network: 192.168.1.184 (add 4)
48th network: 192.168.1.188 (add 4)
49th network: 192.168.1.192 (add 4)
50th network: 192.168.1.196 (add 4)
51st network: 192.168.1.200 (add 4)
52nd network: 192.168.1.204 (add 4)
53rd network: 192.168.1.208 (add 4)
54rd network: 192.168.1.212 (add 4)
55th network: 192.168.1.216 (add 4)
56th network: 192.168.1.220 (add 4)
57th network: 192.168.1.224 (add 4)
58th network: 192.168.1.228 (add 4)
59th network: 192.168.1.232 (add 4)
60th network: 192.168.1.236 (add 4)
61st network: 192.168.1.240 (add 4)
62nd network: 192.168.1.244 (add 4)
63rd network: 192.168.1.248 (add 4)
64th network: 192.168.1.252 (add 4)
65th network: 192.168.1.248 (add 4)

CCNA - Subnetting (IPv4) (6 decks)

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