hw2 answers

Part 1:

A)  A hub works on Layer 1 and just allows for multiple devices to be connected together on a physical level, similarly to them all sharing wires.  A switch works on the data link layer instead of simply connecting the wires together, allowing it to control which ports can send and receive at which times, and therefore segment the collision domains where a hub cannot.

B)  The first diagram (page 1) has two collision domains, one containing all three computers and both hubs, and the other connecting the two switches together.  Because the two hubs and three computers do not have a switch segmenting between the two hubs, they are all part of the same collision domain.  The second diagram (page 2) has 5 collision domains because each port of the routers/switches represents a different domain (so each wire in this example is its own domain).  The third diagram (page 3) also has 5 collision domains because although PC1 and PC2 are plugged into the same switch, it is a switch, so each port is still its own collision domain.

C)  The first diagram has one broadcast domain because it contains no routers, and only routers segment broadcast domains.  The second and third diagrams contain three broadcast domains, one below each router and one between the two routers.

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Part 2:

A)  The two parts of an IP address are the network address and the host address.  The network part comes first, then the host address.  Each host on a network shares the same network address but has its own host address (for example in the second half of part 2, the addresses 10.10.10.1 and 10.10.10.10, where 10.10.10 is the network part).  The value of the first byte specifies the network's class as well as the number of network versus host bytes (however a subnet mask can modify the division of bytes).  Bytes 0-127 (first bit 0) are class A networks (1 network byte, 3 host bytes), bytes 128-191 (first two bits 10) are class B networks (2 network bytes, 2 host bytes), and bytes 192-223 (first three byes 110) are class C networks (3 network bytes, 1 host byte).

B)  Private IP address space allows internal traffic within a local network to not be routed to the Internet.  This allows local networks to remain local such as home networks or private research networks.  For example, nobody can access my home printer that isn't also in my home network.  The technology used for this is Network Address Translation (NAT).

C)  The most complex type of IPv4 address is Class D (reserved for multicast), because it doesn't have a convention/restriction for the number of network and host bytes.

D-I)  The answers to these parts are in the PDF submission.