Briefly explain how to tunnel through the IPv4 cloud.
What will be an ideal response?
To send a packet to a distant IPv6 network through intervening IPv4 routers, the IPv6 packet is formed normally and sent to a router capable of encapsulating it in an IPv4 packet. The routers on both ends of the tunnels must be dual-stack routers, capable of understanding both IPv4 and IPv6. When the interim IPv4 packet reaches the distant IPv6 dual-stack router, that router strips off the IPv4 packet and routes the packet on its local IPv6 network normally. IPv4-compatible IPv6 addresses were designed expressly for this kind of situation, where IPv6 routers need to understand IPv4.
An alternate scheme is the 6to4 tunneling method, as specified in RFC 3056. For IPv4 nodes or networks with public IPv4 addresses, a legitimate IPv6 address is formed by adding the 32 bits of the IPv4 address to the network prefix 2002::/16. This creates an address of the following form: 2002::IPv4address:SLA:Interface_ID. The interface ID is the normal 48 bits, plus the added 16 bits 0xFFFE, and the seventh bit of the first byte inverted, to create a 64-bit EUI-64 formatted IPv6 address (see RFC 4291). The site-level address is the normal 16 bits, and the combination of the 2002::/16 prefix and the 32 bits of the IPv4 address makes up the first 48 bits of the new address.
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(Enforcing Privacy with Cryptography) The explosive growth of Internet communications and data storage on Internet-connected computers has greatly increased privacy concerns. The field of cryptography is concerned with coding data to make it difficult (and hopefully—with the most advanced schemes—impossible) for unauthorized users to read. In this exercise you’ll investigate a simple scheme for encrypting and decrypting data. A company that wants to send data over the In- ternet has asked you to write a program that will encrypt it so that it may be transmitted more se- curely. All the data is transmitted as four-digit integers. Your application should read a four-digit integer entered by the user and encrypt it as follows: Replace each digit with the result of adding 7 to the digit and
What will be an ideal response?
Which of the following is an example of a multilayer authentication?
A. A fingerprint scan and a smart card B. A retina scan and a password C. A retina scan and a fingerprint scan D. A password and a smart card
In certain interfaces, it is necessary to inform users of an abnormal condition or time-dependent information. It is important that the display of this information catches the user's attention. Suggest five ways a designer can successfully attract attention.
What will be an ideal response?
A sequential search
a. Starts with the first element of an array and searches each element until the correct one is found. b. Starts with the last element of an array and searches upward until the correct one is found. c. Starts with the middle element of an array and searches each direction until the correct one is found. d. Does not have to have the array in order.