1.4 SUBNETTING and IP ADDRESSING Flashcards
What do you use to find the number of network IDs for a subnet?
2^x
x = number of borrowed host bits
What do you use to find the number of useable host IP addresses for a subnet?
2^y -2
y = number of bits leftover from network portion
What is VLSM?
Variable Length Subnet Masking, it is the subnetting of subnets, allowing variable number of hosts on each subnet.
What is required for VLSM?
Any modern routing protocol such as RIPv2, IS-IS, BGP, EIGRP, OSPF.
What is significant about /30?
It is used for point-to-point connections due to only having two useable host addresses.
2^0
1
2^1
2
2^2
4
2^3
8
2^4
16
2^5
32
2^6
64
2^7
128
2
2^1
1
2^0
How many subnets are in /30
64
How many subnets are in /29
32
How many subnets are in /28
16
How many subnets are in /27
8
How many subnets are in /26
4
How many subnets are in /25
2
How many subnets are in /24
1
Number of usable hosts in /30
2
Number of usable hosts in /29
6
Number of usable hosts in /28
14
Number of usable hosts in /27
30
Number of usable hosts in /26
62
Number of usable hosts in /25
126
Number of usable hosts in /24
254
What is CIDR? Why is it needed?
Classless Inter-Domain routing. It is a summarization/route aggregation for contiguous networks.
With it only one advertisement needed rather than one for each subnet, greatly reducing routing table size.
