topic 7 : ipv4 address subnetting

Question 1

broadcast domains and segmentation

Answer 1

• many protocols use broadcasts/multicasts
• switches propagate broadcasts out all interfaces except the interface on which it was received from
• only device that stops broadcasts is a router
• routers do not propagate broadcasts
• each router interface connects to a broadcast domain and broadcasts are only propagated within that specific broadcast domain

Question 2

problems with large broadcast domains

Answer 2

1) hosts can generate excessive broadcasts and negatively affect the network

2) solution = reduce the size of the network to create smaller broadcast domains through subnetting

3) dividing the network address (172.17.0.0 /16) into 2 subnets of 200 users each : 172.16.0.0 /24 and 172.16.1.0 /24

4) broadcasts are only propagated within the smaller broadcast domains

Question 3

reasons for segmenting networks (subnetting)

Answer 3

1) reduces overall network traffic and improves network performance

2) can be used to implement security policies between subnets

3) reduces the number of devices affected by abnormal broadcast traffic

4) subnets are used for a variety of reasons including by : location, group/function and device type

Question 4

subnet on an octet boundary

Answer 4

• networks are most easily subnetted at the boundary of /8, /16 and /24
• using longer prefix lengths decreases the number of hosts per subnet