Exercise $3$:

A novice network engineer proposed the network of Figure $7.$ The cloud is just symbolic and represents the Internet. Do not worry too much about it$.$ The computers $($PC$01$ through PC$06)$ are Debian boxes. Using GNS$3,$ implement the network. Power on PC$01,$ PC$02,$ PC$03,$ and PC$05.$ Configure them statically with the network parameters specified in Figure $7.$ Be sure PCO$1,$ PC$02,$ PCO$3,$ and PCO$5$ are statically configured, that is$,$ they should not get their network configuration through DHCP$.$ Now, power on the router and configure it as indicated in Figure $8.$

$```$

Router$>$ enable

Router# configure terminal

Router$($config$)$# hostname R$1$

R$1($config$)$# ip domain name jsu.edu

R$1($config$)$# interface FastEthernet $0/0$

R$1($config$-$if$)$# ip address $20\mathrm{.}0\mathrm{.}0\mathrm{.}6255\mathrm{.}255\mathrm{.}255\mathrm{.}248$

R$1($config$-$if$)$# no shutdown

R$1($config$-$if$)$# exit

R$1($config$)$# ip dhcp pool MYPOOL

R$1($dhcp$-$config$)$# network $20\mathrm{.}0\mathrm{.}0\mathrm{.}0255\mathrm{.}255\mathrm{.}255\mathrm{.}248$

R$1($dhcp$-$config$)$# domain$-$name jsu.edu

R$1($dhcp$-$config$)$# default$-$router $20\mathrm{.}0\mathrm{.}0\mathrm{.}6$

R$1($dhcp$-$config$)$# dns$-$server $8\mathrm{.}8\mathrm{.}8\mathrm{.}8$

R$1($dhcp$-$config$)$# lease $0010$

R$1($dhcp$-$config$)$# end

$```$

Figure $8$: Configuration of the Router for the Second Experiment with DHCP

Question $3\mathrm{.}1$:

Start capturing the network traffic with Wireshark in any link connected to the hub. Turn on PCO$4.$ Make sure it gets$/$got its network configuration through DHCP$.$ What is the IP address obtained by this computer? How does the DHCP server realizes that $20\mathrm{.}0\mathrm{.}0\mathrm{.}1,20\mathrm{.}0\mathrm{.}0\mathrm{.}2,$ and $20\mathrm{.}0\mathrm{.}0\mathrm{.}3$ are already in use? Check the DHCP pool, DHCP binding, and DHCP conflict $($show ip dhep conflict$)$ in the router.

Question $3\mathrm{.}2$:

Make sure you are still capturing the network traffic. If it is not the case anymore, start a new capture. Power on PCO$6$ and make sure it is$/$was configured to acquire its network configuration through DHCP$.$ What is the IP address obtained by this computer? What is happening?