We have already covered the topic of network addresses. The first (1) in a block (in classes A, B, and C) defines the network address. In classes A, B, and C,if the hostid is all ls,the address is called a direct broadcast address. It is used by a(2) to send a packet to all hosts in a specific network. All hosts will accept a packet having this type of destination address. Note that this address can be used only as a (3) address in an IP packet. Note also that this special address also reduces the number of available hostid for each netid in classes A,B，and C． In classes A, B, and C, an address with all ls for the netid and hostid (32bits) define a (4) address in the current network.A host that wants to send a message to every other host can use this address as a destination address in an IP packet. However, a router will block a packet having this type of address to confine the broadcasting to the (5) network. Note that this address belongs to class E. 空白（3）处应选择（）-计算机网络管理员-总题库

"I’m a total geek all around," says Angela BYron, a 27-year-old computer prlogrammer who has just graduated from Nova Scotia Community College. And yet, like many other students, she "never had the confidence" to approach any of the various open-source software communities on the internet--distributed teams of volunteers who collaborate to build software that is then made freely available. But thanks to Google, the world’s most popular search engine and one of the biggest proponents of open-source software, Ms Byron spent the summer contributing code to Drupal, an open-source project that automates the management of websites. "It’s awesome," she says.
Ms Byron is one of 419 students (out of 8 744 who applied) who were accepted for Google’s "summer of code". While it sounds like a hyper-nerdy summer camp, the students neither went to Google’s campus in Mountain View, California, nor to wherever their mentors at the 41 participating open-source projects happened to be located. Instead, Google acted as a matchmaker and sponsor. Each of the participating open-source projects received ＄500 for every student it took on; and each student received ＄4 500 (＄ 500 right away, and ＄4 000 on completion of their work). Oh, and a T-shirt.
All of this is the idea of Chris DiBona, Google’s open-source boss, who was brainstorming with Larry Page and Sergey Brin, Google’s founders, last year. They realised that a lot of programming talent goes to waste every summer because students take summer jobs flipping burgers to make money, and let their coding skills degrade. "We want to make it better for students in the summer," says Mr. DiBona, adding that it also helps the open- source community and thus, indirectly, Google, which uses lots of open source software behind the scenes. Plus, says Mr. DiBona, "it does become an opportunity for recruiting."
Elliot Cohen, a student at Berkeley, spent his summer writing a "Bayesian network toolbox" for Python, an open-source programming language. "I’m a pretty big fan of Google," he says. He has an interview scheduled with Microsoft, but "Google is the only big company that I would work at," he says. And if that doesn’t work out, he now knows people in the open-source community, "and it’s a lot less intimidating./
The idea of Chris DiBona, according to the text, is enriched by ______.

A:T shirt sales B:open-source C:programmers’ talent D:others’ wisdom

One of the main responsibilities of ICMP is to report ______. Although technology has produced increasingly reliable transmission media, errors still exist and must be handled. IP is an ______ protocol. This means that error checking and error control are not a concem ofIP JCMP wasdesigned, in part, to compensate for this shortcoming. Howerver, ICMP does not ______ errors, itsimply reports them. Error correction is left to the higher-level protocols. Error messages arealways sent to the original ______ because the only information available in the datagram aboutthe route is the source and destination 1P addresses. ICMP uses the source IP address to send theerror massage to the source of the ______.

A:user B:destination C:source D:Program

One ofthe main resposibilities of ICMP is to report(1).Although technology has produced increasingly relaible transmission media, errors still exist and must be handled. IP is an (2) protocol. This means that error checking and error control are not a concern of IP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP does not (3) errors, it simply report them. Error correction is left to the higher-level potocols. Error messages are always sent to the original (4) because the only information available in the datagram about the route is the source and destination IP addresses. ICMP use the source IP address to sent the error massage to the source of the (5).

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