1.Explain the working of trace route.Trace route works by increasing the time-to-live value of every successive packets sent in batch. Every three packets that were sent first, have a time-to-live value 1. The next three packets have a TTL value of 2 and so on. The host decrements the TTL value by one and the packet is forwarded to the next host, when a packet passes through a host.When a packet (with a time-to-live value of 1) reaches a host, the packets will be discarded by the host, and an ICMP time exceeded packet is sent to the sender. A list of hosts, whose packets have traversed enrouted to the destination, is utilized by the trace route utility.2.Explain the following terms: ICMP, ARP, Multicast, Broadcast?Internet Control Message Protocol: This protocol is used for while checking the connectivity using ping commandAddress Resolution Protocol: This protocol is used to know about the properties of TCP/IP. For example, to know other system MAC addresses.Multicast: Communication between single sender and a list of select recipients in a network.Broadcast: To send messages to all the recipients simultaneously in a network.3.What is meant by the term 'IP Spoofing'?IP Spoofing:Sending messages by intruder to a computer system with an IP address that indicates the message is sent from a trusted host, for gaining unauthorized access to computer systems. The hacker / intruder first utilize a variety of techniques for finding an IP address of a trusted host. Later he modifies the packet headers, in order to give an illusion that the packets are sent from the host.4.Explain the term 'DOS attack'.A Denial Of Service attack. It attempts for making computer resources unavailable to its intended users. Its concerted efforts of a person are to prevent a site or service from functioning efficiently, temporarily or indefinitely. The target site categories are banks, credit card payment gateways and root name servers.

5.Need for cross layer design.Significant performance advantages (e.g. 10 dB in certain situations). Forces designers to consider other layers. Layers are coupled.

6.Hidden node problem.Node A wants to transmit a message to Node B. Node C wants to transmit a message to Node D. Without coordination Node Cs signal will interfere with As transmission to Node B. Node C might start its transmission after A has already begun transmitting because C can not hear Node As signal. This is the hidden node problem

7.Application of multilayer design. Real time media and QOS support Hard delay/quality constraints8.Cross layer adaptive techniques. Link, MAC, network, and application adaptation Resource management and allocation (power control) Synergies with diversity and scheduling9.Cross layer scheduling Application scheduling/data prioritization Resource reservation Access scheduling 10. Mobile IP was originally designed to support macro mobileity 11Uses a hierarchical approach to minimize registrations to home agents as a mobile host roaming around. 12.A foreign agent can provide services to multiple base station. 13.Hawaii protocol Adopts a domain-based approach in which base stations can be connected as a tree. 14. It uses specialized path setup schemes that install host-based forwarding entries in specific routers to support intradomain routing. 15. Manets multihop nature requires setting the TTL to N and decreasing the value by one for each reboadcast 16. To prevent broadcast datagram from looping back to the source host The broadcast daemon also records broadcast datagram that it has encapsulated recently