Chapter Questions
Given a small set of hardware addresses (positive integers), can you find a function $f$ and an assignment of IP addresses such that $f$ maps the IP addresses 1-to-1 onto the physical addresses and computing $f$ is efficient?
In what special cases does a host connected to an Ethernet not need to use ARP or an ARP cache before transmitting an IP datagram? (Hint: what about multicast?)
One common algorithm for managing the ARP cache replaces the least recently used entry when adding a new one. Under what circumstances can this algorithm produce unnecessary network traffic?
Should ARP software modify the cache even when it receives information without specifically requesting it? Why or why not?
Any implementation of ARP that uses a fixed-size cache can fail when used on a network that has many hosts and heavy ARP traffic. Explain how.
ARP is often cited as a security weakness. Explain why.
Suppose machine $C$ receives an ARP request sent from $A$ looking for target $B$, and suppose $C$ has the binding from $I_s$ to $H_s$ in its cache. Should $C$ answer the request? Explain.
ARP can prebuild a cache for all possible hosts on an Ethernet by iterating through the set of possible IP addresses and sending an ARP request for each. Is doing so a good idea? Why or why not?
Should early revalidation send a request for all possible IP address on the local network, all entries in the ARP cache, or only for destinations that have experienced traffic recently? Explain.
How can a computer use ARP at boot time to find out if any other machine on the network is impersonating it? What are the disadvantages of the scheme?
Explain how sending IPv4 packets to nonexistent addresses on a remote Ethernet can generate broadcast traffic on that network.
Suppose a given Ethemet switch connects 4095 hosts and a router. If $99 \%$ of all traffic is sent between individual hosts and the router, does ARP or NDP incur more overhead?
Answer the previous question for the case where traffic is uniformly distributed among random pairs of hosts.