a. The arp command: arp -s InetAddr EtherAddr allows you to manually add an entr

Question

a. The arp command:

arp -s InetAddr EtherAddr

allows you to manually add an entry to the ARP cache that resolves the IP addressInetAddr to the physical address EtherAddr. What would happen if, when you manually added an entry, you entered the correct IP address, but the wrong Ethernet address for that remote interface?

b. What is the default amount of time that an entry remains in your ARP cache before being removed. You can determine this empirically (by monitoring the cache contents) or by looking this up in your operation system documentation. Indicate how/where you determined this value.

Explanation / Answer

a.) The arp command allows us to add an entry to arp cache that resolve the (internet add.) to the physical(ethernet) address.

if we manualy add an entry with correct ip address, and incorrect ethernet address, basicly arp assign address dynamicaly but ip address is static. so if we have to change it then we have to manualy update the network or manualy delete the ip address.

now we add correct internet address and incorrect ethernet, then

arp -s 111.111.111.1 aa-af-ab-11-2c-2f

then it will add this as static network address type.

so then we start transmitting packets to this ip address.

case1- if we are using fake network address like incorect ip or incorrect ethernet

there will be full 100% loss of packets occur because of fake ethernet of ip address.

case2- if ip address and ethernet are correct then packet is transmitted .

so no loss occur in this case.

b.) arp cache has time-out value for added ip address to it. it will remove these addresses once given time out time is over.

so every ip address in arp cache stayed for fixed unit of time and that fixed time is maximum 10 minutes before removal of added ip address .

(how you determined this value)-it is specified in documentation of arp cache.

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