HW3 Prelab

hw3prelab.md

1. What is the IOS command to change the MTU (Max Transimission Rate) for an interface on a Cisco router?
2. How does a router determine whether datagrams to a particular host can be directly delivered through one of its interfaces?
3. Which systems generate ICMP route redirect messages-- routers, hosts , or both?
4. What is the default maximum TTL value used by traceroute when sending UDP datagrams?
5. Describe the role of a default gateway in a routing table?
6. What is the network prefix of IP address 192.110.50.3/24?
7. Explain the difference between a network IP address and a network prefix.
8. An organization has been assigned the network number 140.25.0.0/16 and it neeeds to create networks that support up to 60 hosts on each IP network. What is the max number of networks that can be set up? Explain.

Answers

1. One can use: interface ethernet <interface> followed by ip mtu [mtu value] to change the MTU on a Cisco router.

2. A router uses the IP header of the packets to check if it knows the end destination of the packet by checking against the IP routing tables on the machine. If the destination cannot be found, then the packets wont make it but if it is found, then the router sends that packet through its interface.

3. Routers generate redirect ICMP route redirect messages in order to inform hosts sending traffic through that particular router of other, better paths to send traffic to target hosts.

4. The maximum TTL value used by traceroute according to the tciplab.net man page is a value of 30 hops max

5. The default gateway lives up to its name and is chosen as the default next stop for an IP that cant be found in the routing table. It provides a out of the network for packets who's destination can't be found.

6. The network prefix of the IP is: /24

7. A network IP address is the network part of IP address. In this context it is the address that other machines on the network refer to the machine as. A network prefix defines the span of the network that exists only on the host machine that defines its own addressable-network, with all devices on that network starting at the prefix. It defines the number of bits necessary to identify between network and host.

8. An organization assigned the network number 140.25.0.0./16 has a subnet mask of 255.255.0.0 meaning that it thinks it connected to all of the network 140.25.0.0 meaning that it can address 2^16 sub-networks at max but it requires at least 6 bits to address the 60 host (64 max) , leaving 10 bits for sub networks that can address 60 hosts or around 1,024 networks