Question

each ip address class has a default subnet mask which uses the whole octet for either network bits or host bits.
select the default subnet mask in binary then dotted decimal for each class below.
class a binary select
decimal s
class b binary
decimal select
class c binary select
decimal select

Explanation:

Step1: Class A Subnet Mask

Class A has the first octet as network bits. The default subnet mask in binary is \(11111111.00000000.00000000.00000000\).
To convert to decimal:

• First octet: \(11111111_2 = 255_{10}\)
• Second - fourth octets: \(00000000_2=0_{10}\)

So decimal is \(255.0.0.0\)

Step2: Class B Subnet Mask

Class B has the first two octets as network bits. The binary subnet mask is \(11111111.11111111.00000000.00000000\)

• First two octets: \(11111111_2 = 255_{10}\)
• Third - fourth octets: \(00000000_2 = 0_{10}\)

Decimal is \(255.255.0.0\)

Step3: Class C Subnet Mask

Class C has the first three octets as network bits. Binary subnet mask is \(11111111.11111111.11111111.00000000\)

• First three octets: \(11111111_2=255_{10}\)
• Fourth octet: \(00000000_2 = 0_{10}\)

Decimal is \(255.255.255.0\)

Answer:

Class A Binary: \(11111111.00000000.00000000.00000000\), Decimal: \(255.0.0.0\)
Class B Binary: \(11111111.11111111.00000000.00000000\), Decimal: \(255.255.0.0\)
Class C Binary: \(11111111.11111111.11111111.00000000\), Decimal: \(255.255.255.0\)