5A Flashcards
Subnets is short for what?
Subnetworks
A ____ then, is a logical division of a network of connected network
devices based on the IP address.
Subnet
A subnet is a separate and identifiable portion of an organization’s
network, typically arranged on one floor, building or geographical location. Consider a subnet a…?
network within a network
Each device on each subnet has an IP address that logically associates it with the others on the same subnet. This also prevents devices on one subnet from getting confused with hosts on the other subnet. In terms of IP addressing and subnets, these devices are referred to as ____.
hosts
So, in our example, there is a ____ (the company), which is divided into ___ ___ (marketing and sales departments), each of which has its own ____ (users and printers).
network
logical subnets
hosts
To subnet a network is to create ___ ___ of the network.
logical divisions
Subnetting, therefore, involves dividing the network into smaller portions called ____.
subnets
Subnetting applies to __ ____ because this is done by borrowing bits from the host portion of the IP address.
IP addresses
In a sense, the IP address then has three components - the ____ part, the ____ part and, finally, the ____ part.
network part
subnet part
host part
We create a subnet by logically grabbing the ____ ____ from the network component of the address and using it to determine the number of subnets required.
last bit
Class C address normally has 24 bits for the network address and eight for the host, but we are going to borrow the ____-____ bit of
the host address and declare it as identifying the subnet.
left-most
If the bit is a 0, then that will be one subnet; if the bit is a 1 that would be the ___ subnet.
second
A subnet mask is a __-___ number used to differentiate the network component of an IP address by dividing the IP address into a network address and host address.
32-bit number
All that a subnet mask does is indicate how many bits are being
“____” from the host component of an IP address. If you can’t remember anything about subnetting, remember this concept. It is the foundation of all subnetting.
borrowed
The reason a subnet mask has this name is that it literally ___ ___ the host bits being borrowed from the host address portion of the IP address.
masks out
The /25 is a format known as…?
ClDR
What does CIDR stand for?
Classless Internet Domain Routing
IP addresses classes are not ___ ___ other than to understand the basic concepts of IP addressing.
used anymore
Instead, Classless Internet Domain Routing (CIDR), pronounced “___”, is used to represent IP addresses.
cider
The idea behind CIDR is to adapt the concept of subnetting to the ___ ___.
entire internet
In short, classless addressing means that instead of breaking a particular network into subnets, we can aggregate networks into larger ____.
supernets
CIDR is therefore often referred to as ______, where the principles of subnetting are applied to larger networks.
supernetting
CIDR is written out in a ___/___ format, where the mask is tacked onto the network address in the form of the number of bits used in the mask. An example would be 205.112.45.60/25.
network/mask
What is most important to understand about the CIDR method of subnetting is the use the ___ ___ (the /25 of 205.112.45.60/25), rather than the classful way of using the first three bits of the IP address to determine the dividing point between the network number and the host number.
network prefix
So why use CIDR? Because it’s a much more ____ ____ of the IP address space. Using CIDR, a network admin can carve out several host addresses that’s closer to what is required than with the class approach.
efficient allocator
When an IP network is assigned more than one subnet mask, it is said to a have a…?
VLSM
What does VLSM stand for?
Variable Length Subnet Mask
This is what is used when you are subnetting a subnet. The concept is very straightforward: Any one subnet can be broken down into further subnets by indicating the proper ____.
VLSM
This makes IP addressing more efficient by allowing each subnet to have a different number of hosts. This results in reducing the number of ___ ___.
wasted addresses
Up to ____ Available Subnets per class A address.
8,388,608
Provides most available subnets because class _ has
more host bits to borrow from.
Class A
Up to _____ available subnets per class B address.
32,768
Is a Classless Inter-Domain Routing replaced antiquated classful
routing.
CIDR
The relevance of this is that RIP1 only allows a ___ ___ ___, making it impossible to get the full benefit of VLSM. You must use a newer routing protocol like Open Shortest Path First (OSPF) or RIP2, where the network prefix length or mask value is sent along with route advertisements from router to router. With these in use, it is possible to use VLSM to its full potential and have more than one subnet or sub-subnets.
single subnet mask
Designing and setting up a simple network isn’t complicated. It is based on two things; how many ____ needed and/or how many ____ needed for the subnet.
subnets and hosts needed
