An IPv4 address is written as 4 decimal numbers separated by dots (dotted-decimal notation). Each number is ____ bits long.
Each number is 8 bits long, i.e. an octet.
For example, 192.168.1.42 can also be written as 4 binary octets
11000000 10101000 00000001 00101010
What is an IP address used for?
To uniquely identify a device on a network.
How does an IPv4 address identify a device?
Some number of bits in the address identify the network and the remaining bits identify the device, i.e. the host. E.g. the first 24 bits might be used to identify the network and the last 8 bits the host.
What is a subnet?
A logical subdivision of an IP network.
How do you know how many bits in an IPv4 address are being used to describe the network and how many to describe the host?
A subnet mask.
How does a subnet mask identify the network bits and host bits in an IPv4 address?
The subnet mask itself looks like an IPv4 address. It uses binary 1s to indicate network bits and binary 0s to indicate host bits.
For example, a subnet mask of 255.255.255.0 looks like this in binary:
11111111 11111111 11111111 00000000
This subnet mask says that the first 24 bits of an associated IPv4 address describe the network and the last 8 bits describe the host (device).
What is CIDR?
Classless inter-domain routing, a method for efficiently allocating and managing IP addresses.
What is CIDR notation?
A compact representation of an IP address and its associated network mask. CIDR notation specifies an IP address, a /, and a decimal number (also called the prefix). The decimal number is the count of consecutive leading 1 bits (from left to right) in the network mask. In other words, the prefix number after the slash tells you how many bits in the IP address will be used to describe the network address.
What is Variable Length Subnet Masking (VLSM)?
The ability to use different subnet masks within a single network to create subnets of different sizes. CIDR uses VLSM to alter the ratio of network and host address bits in an IP address.
What’s an example of a CIDR notation that describes a single IP address?
192.168.1.5/24
describes a single IP address of 192.168.1.5 with a subnet mask of 255.255.255.0 (24 consecutive 1s).
What’s an example of a CIDR notation that describes a block of IP addresses?
198.51.100.0/22 describes a block of 1,024 IP addresses beginning at 198.51.100.0 and ending at 198.51.103.255.
Also called a CIDR range.
How do you calculate the network address from a CIDR notation?
The address you get if all host bits are 0.
How do you calculate the broadcast address from a CIDR notation?
The address you get if all host bits are 1.
What is the significance of the broadcast address?
Every device in the subnet listens for packets sent to the broadcast address.
Can you deduce the subnet mask from CIDR notation?
Yes, because the prefix tells you how many bits describe the network. These are the bits set to 1 in the subnet mask.
How does a CIDR range describe a block of IP addresses?
The prefix, which is the number after the slash, tells you how many bits in the IP address describe the network. Subtracting the prefix from 32 tells you how many bits are available for hosts in the block. If you zero out the host bits in the IP address of the CIDR notation, you get the network address. To enumerate the IP addresses in the block, begin counting up from the network address until you exhaust all the host bits. When you reach an octet boundary (255), increment the number in the octet to the left and reset the count in the current octet to 0.
True or False
The number of addresses in an IPv4 CIDR range notation may be calculated as 2^(32-prefix length).
True
Fill in the blank
Network Address Translation (NAT) translates a local, private IP address to an ____________ IP address.
Internet-ready
Fill in the blank
NAT enables a local network to use a private IP range that is ____________ on the Internet.
nonroutable
Fill in the blank
A NAT device ____________ the existence of the local network.
hides (or obscures)
Fill in the blank
A NAT device serves as a ____________ for computers on a local network to access the Internet.
gateway
Fill in the blank
A NAT device that receives packets from the Internet will ____________ those packets using the local address scheme.
route
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Module 1 - Introduction to the Cloud25
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Module 2 - Compute in the Cloud86
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Module 3 - Exploring Compute Services56
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Module 4 - Going Global25
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Networking Concepts22
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Module 5 - Networking74
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Module 6 - Storage115
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Module 7 - Databases43
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Module 8 - AI ML and Data Analytics76
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Module 9 - Security64
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Module 10 - Monitoring, Compliance, and Governance in the AWS Cloud71
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Module 11 - Pricing and Support57
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Module 12 - Migrating to the AWS Cloud45
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Module 13 - Well-Architected Solutions33
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Extra Stuff16
