子网计算专题.doc

子网计算专题IP地址和子网掩码计算实例IP地址和子网掩码两者是相辅相成的，子网掩码2进制中的“1”对应的IP地址部分是网络地址，“0”对应主机地址，计算一个IP地址的网络地址、主机地址、广播地址就是根据子网掩码来确定的； 划分子网就是从主机中借N位来作为子网位，因此增加了网络的个数，同时牺牲了一定的主机数；公式：根据2s-2=所需的子网数 （s为子网位数） 根据2h-2=所需的主机数 （h为主机位数）实例1：IP地址192.168.1.200，子网掩码是255.255.255.224，请计算出网络地址、主机地址和广播地址。 解法一：把子网掩码换算成2进制，1对应的部分是网络地址，0对应的部分是主机地址，把主机地址各位全部变成1就是广播地址。因此首先把255.255.255.224换算成2进制，就是11111111.11111111.11111111.11100000，然后把IP地址也换算成2进制，就是11000000.10101000.00000001.11001000，因此可以得到网络地址就是11000000.10101000.00000001.11000000，即192.168.1.192；主机地址就是00001000；而广播地址就是11000000.10101000.00000001.11011111，即192.168.1.223。解法二：掩码255.255.255.224可知道这个掩码所容纳的IP地址有256-224=32个（包括网络地址和广播地址），那么具有这种掩码的网络地址一定是16的倍数。而网络地址是子网IP的开始，广播地址是结束，可使用的IP地址在这个范围内。32的倍数有：0、32、64、96、128、160、192、224等。主机的IP地址是192.168.1.200，在192和224之间，那么网络地址就是192.168.1.192，而广播地址就是下一个网络的网络地址减一。而下一个网络地址是224，因此可以得到广播地址为192.168.1.223。 实例2：一个公司有10个部门，要求给每个部门划分不同的网段，但是都在192.168.1.0这个大网内，并且每个部门要容纳20台计算机。请为这个公司选择子网掩码。 分析：首先看关键数据，10个部门共要10个网段的子网，也就是说采用的子网掩码要支持10个有效的子网，而且还要求每个子网容纳20个有效的主机地址。 根据2的N次方减2的公式，10介于2的3次方和2的4次方之间，因此应该从主机位借4位来作为子网位，二进制就是11111111.11111111.11111111.11110000，即255.255.255.240。有些人就毫不犹豫地选择了255.255.255.240作子网掩码。但是真的就这样计算结束了吗？其实不然。我们知道，C类地址主机位本来就只有8位，现在已经借去4位，剩下4位，因此每个子网能够允许的主机数量为2的4次方减2，即14台计算机。而题目要求每个子网容纳主机20台，看来是无法达到目的。同样如果我们先从主机数量着手计算，应该采用255.255.255.224的子网掩码，但是这个掩码只能允许有6个有效的子网，因此同样无法满足10个子网的要求。实例3：判断两台计算机的IP地址是否属于同一个子网。主机A：I P 地址 16. 73.129.233，子网掩码 255.255.128.0 主机B：I P 地址 16. 73.129.1子网掩码255.255.128.0计算主机A网络号： I P 地址 16. 73.129.233子网掩码 255.255.128.0-转化为二进制进行运算： I P地址00010000.01001001.10000001.11101001子网掩码 11111111.11111111.10000000.00000000-AND运算 00010000.01001001.10000000.00000000-十进制 16. 73 .128 .0计算主机B网络号：I P 地址 16. 73.129.1子网掩码255.255.128.0- 转化为二进制进行运算：-I P 地址00010000.01001001.10000001.00000001子网掩码11111111.11111111.10000000.00000000- AND运算 00010000.01001001.10000000.00000000-十进制 16. 73 .128 .0通过以上对2组计算机IP地址与子网掩码的AND运算后，我们可以看到它运算结果是一样的。均为16.73.128.0，所以计算机就会把这2台计算机视为是同一子网络。IP地址专题你有一个网络需要29个子网，为了提供正确的子网，子网需要向主机位借多少位？A.2 B.3 C.4 D.5答案：D：根据公式2n29得到n=5IP地址是200.10.5.68/28，该主机所在的子网是多少？（C）A.200.10.5.56 B.200.10.5.32 C.200.10.5.64 D.200.10.5.0答案：C；/28是255.255.255.240，256-240=16，所以子网为0、16、32、48、64、80等；该主机在64子网中。网络地址172.16.0.0/19提供了多少子网和多少主机数？A.7个子网，每个子网30个主机 B.7个子网，每个子网2046个主机8个子网，每个子网2046个主机 D.8个子网，每个子网8190个主机答案：D。/19的CIDR地址是255.255.224.0，这是一个B类网络，他只有3个子网位（8个子网），13个主机位提供213-2=8190公司希望合并192.24.32.0/24192.24.39.0/24，使用子网掩码255.255.248.0,一共能容纳多少台主机？（A）A.2046 B.2032 C.8190 D.254某公司使用TCP/IP作为唯一的传输协议。网络不需连到internet，你使用172.30.0.0/16网段。为了提高性能和适应公司业务增长，你需要对网络划分进行优化。你分了25个子网，每个子网最多1000台主机。然而公司业务又有增长需要55个子网，每个子网最多1000台主机。如何设置掩码？(C) A.255.255.240.0 B.255.255.248.0 C.255.255.252.0 D.255.255.254.0网络中有1900台主机，没有路由。你从ISP获得如下网段： 192.24.32.0/24； 192.24.33.0/24； 192.24.34.0/24； 192.24.35.0/24； 192.24.36.0/24； 192.24.37.0/24； 192.24.38.0/24； 192.24.39.0/24；你希望简化路由表，如何设置掩码？ (B)A.255.255.252.0 B.255.255.248.0 C.255.255.255.248 D.255.255.240.0128.0.0.1 属于哪一类的IP地址？(B)A.A类IP地址 B.B类IP地址 C.C类IP地址 D.D类IP地址您的办事处将要组建一个大约包含150台计算机的小型网络。您希望将其子网化，并且最近也没有将其连往Internet的计划。因此，您将组建一个专有的企业内部网。如果您希望使用B类网络ID，下列的网络ID和子网掩码中，您的网络可以使用的有效选择是哪一组? (D) A.网络ID10.0.1.0，子网掩码255.255.0.0 B.网络ID132.127.0.0，子网掩码255.255.255.0 C.网络ID192.168.0.1，子网掩码255.0.0.0 D.网络ID172.16.0.0，子网掩码255.255.0.0 某公司的局域网通过代理服务器，使用ADSL上网，同时局域内的用户彼此间可以通信，下面哪一组网络IP地址将是最好的选择？(B)A、23.X.X.X/8 B、172.16.X.X/16 C、194.150.X.X./24 D、206.100.X.X/16网络中的客户机在启动计算机时会自动向DHCP申请地址，当DHCP不在线时，客户机可以得到的IP地址为：（D） A.10.0.0.0 B.192.168.0.0 C.172.16.0.0 D.169.254.0.0在默认情况下，B类IP地址的子网掩码是多少？ (B) A. 255.0.0.0 B. 255.255.0.0 C. 255.255.255.0 D. 255.255.255.255 对于子网224.240.16.0，哪一个子网掩码是无效的? C A.255.255.255.192 B.255.192.0.0 C.255.192.255.0 D.255.255.192.0 在C类地址197.15.22.31和子网掩码255.255.255.224的情况下，借了多少位来创建子网? (C) A. 1 B. 2 C. 3 D. 上述答案都不对 以下_B_不是一个合法的因特网IP地址。A90.51.98.172 B200.219.257.140 C202.99.96.140 D158.227.100.12一个ISP有一个地址块206.0.64.0/18,它为一个用户分配的地址块是206.0.64.0/22，用户可使用的地址空间是（D）。A512 B4096 C2048 D1024当一台路由器在IP地址211.8.2.5和255.255.0.0进行“与”操作时，网络地址是什么？B A. 211.8.1.0 B. 211.8.0.0 C. 211.8.2.0 D. 上述答案都不对采用可变长子网掩码技术可以把大的网络分成小的子网，例如把子网掩码为255.255.0.0的网络40.15.0.0分为两个子网，假设第一个子网为40.15.0.0/17，则第二个子网为(1)。假设用户Xl有2000台主机，则至少应给他分配(2)个C类网络，如果分配给用户Xl的网络号为196.25.64.0，则指定给Xl的子网掩码为 (3)；假设给用户X2分配的C类网络号为196.25.16.0196.25.31.0，则X2的子网掩码应为(4)：如果路由器收到一个目标地址为11000100.00011001.01000011.00100001的数据报，则该数据报应送给(5)用户。1.A40.15.1.0/17 B40.15.2.0/17 C40.15.100.0/17 D40.15.128.0/17 2.A4 B8 C10 D16 3.A255.255.255.0 B255.255.250.0 C255.255.248.0 D255.255.240.0 4.A255.55.255.0 B255.255.250.0 C255.255.248.0 D255.255.240.0 5.AXl BX2 CXl和X2 D非Xl且非X2 答案：DBCDA172.16.5.3/16划分50个子网，每个子网的网络号和IP地址范围？（写出前八个）123公司原来的网络为172.16.0.0/16,经过努力现在公司逐渐发展壮大起来，如今公司有6个部门，分别是销售部（220人），开发部（150人），行政部（40人），会计部（10人），经理室（4人），董事长室（2人），所以要进行子网划分，同时也希望能尽量节省IP资源，请写出子网的网络号和IP地址范围。 设有下面4条路由：172.18.129.0/24、172.18.130.0/24、172.18.132.0/24和172.18.1330/24，如果进行路由汇聚，能覆盖这4条路由的地址是_(49)_A。（49）A. 172.18.128.0/21 B. 172.18.128.0/22C. 172.18.130.0/22 D. 172.18.132.0/23 网络122.21.136.0/24和122.21.143.0/24经过路由汇聚，得到的网络地址是_(50)_B_。（50）A. 122.21.136.0/22 B. 122.21.136.0/21C. 122.21.143.0/22 D. 122.21.128.0/24IP 地址相关练习题1、Your junior network administrator wants to know what the default subnet mask is for a Class C IP address. What do you tell him? A. 255.0.0.0 B. 255.255.0.0 C. 255.245.255.0 D. 255.255.255.0 E. 255.255.255.2552、You are designing a network, which needs to support 55 users. You dont plan to extend the segment beyond the current number of users. Which subnet mask would best meet your needs? A. 255.255.0.0 B. 255.255.255.0 C. 255.255.255.192 D. 255.255.255.1603、 You have added a new switch to your network. You want to manage it remotely, so you need to assign it an IP address. Your router that connects to the switch has an IP address of 172.16.12.33/27. Which of the following addresses can you assign to this switch? A. 172.16.12.33/28 B. 172.16.12.32/27 C. 172.16.12.33/27 D. 172.16.12.34/27 E. 172.16.12.35/28 F. 172.16.12.38/28 G. 172.16.12.63/274、The address 172.16.208.16/20 is a host address in which of the following subnets? A. 172.16.176.0255.255.240.0 B. 172.16.192.0255.255.240.0 C. 172.16.208.0255.255.240.0 D. 172.16.224.0255.255.240.0 5、You are designing an IP address scheme for your brand new remote office. The vice president of IT calls to tell you that you will be in charge of the 192.168.1.64/26 subnetwork. This supplies you with a single subnetwork with 62 hosts. You need to have at least two subnets with 14 hosts in each subnet. What custom subnet mask should you use? A. 255.255.255.128 B. 255.255.255.192 C. 255.255.255.224 D. 255.255.255.240 E. 255.255.255.2486、You have subnetted the 210.106.14.0 network with a /24 mask. Your boss at Acme, Inc. wants to know how many usable subnetworks and usable host addresses per subnet this would provide. What should you tell her? A. One network with 254 hosts B. Two networks with 128 hosts C. Four networks with 64 hosts D. Six networks with 30 hosts 7、Identify three valid host addresses in any subnet of the 201.168.27.0 network, assuming a fixed subnet mask of 255.255.255.240. (Choose three.) A. 201.168.27.33 B. 201.168.27.112 C. 201.168.27.119 D. 201.168.27.126 E. 201.168.27.175 F. 201.168.27.2088、What is the subnetwork address for a host with the IP address 201.100.5.68/28?A. 201.100.5.0 B. 201.100.5.32 C. 201.100.5.64 D. 201.100.5.65 E. 201.100.5.31 F. 201.100.5.1 9、your junior network administrator wants to know what the default subnet mask is for a class c ip address. what do you tell him? a. 255.0.0.0 b. 255.255.0.0 c. 255.245.255.0 d. 255.255.255.0 e. 255.255.255.255 10、you are designing a network, which needs to support 55 users. you dont plan to extend the segmentbeyond the current number of users. which subnet mask would best meet your needs? a. 255.255.0.0 b. 255.255.255.0 c. 255.255.255.192 d. 255.255.255.160 11、you have added a new switch to your network. you want to manage it remotely, so you need to assign it an ip address. your router that connects to the switch has an ip address of 172.16.12.33/27. which of the following addresses can you assign to this switch? a. 172.16.12.33/28 b. 172.16.12.32/27 c. 172.16.12.33/27 d. 172.16.12.34/27 e. 172.16.12.35/28 f. 172.16.12.38/28 g. 172.16.12.63/27 12、the address 172.16.208.16/20 is a host address in which of the following subnets? a. 172.16.176.0255.255.240.0 b. 172.16.192.0255.255.240.0c. 172.16.208.0255.255.240.0 d. 172.16.224.0255.255.240.013、you are designing an ip address scheme for your brand new remote office. the vice president of it calls to tell you that you will be in charge of the 192.168.1.64/26 subnetwork. this supplies you with a single subnetwork with 62 hosts. you need to have at least two subnets with 14 hosts in each subnet. what custom subnet mask should you use? a. 255.255.255.128 b. 255.255.255.192 c. 255.255.255.224d. 255.255.255.240 e. 255.255.255.24814、you have subnetted the 210.106.14.0 network with a /24 mask. your boss at acme, inc. wants to know how many usable subnetworks and usable host addresses per subnet this would provide. what should you tell her? a. one network with 254 hosts b. two networks with 128 hostsc. four networks with 64 hosts d. six networks with 30 hosts15、identify three valid host addresses in any subnet of the 201.168.27.0 network, assuming a fixed subnet mask of 255.255.255.240. (choose three.)a. 201.168.27.33 b. 201.168.27.112 c. 201.168.27.119d. 201.168.27.126 e. 201.168.27.175 f. 201.168.27.208 16、what is the subnetwork address for a host with the ip address 201.100.5.68/28? a. 201.100.5.0 b. 201.100.5.32 c. 201.100.5.64 d. 201.100.5.65 e. 201.100.5.31 f. 201.100.5.117、you are planning on using a single network that supports 208 users. which ip address class would you choose to be the most efficient? a. class a b. class b c. class c d. class d e. class e 18: rfc 1918 defines the private ip address ranges. which of the following ip addresses are considered part of these ranges? (choose three.)a. 10.23.45.67 b. 126.21.34.56 c. 172.16.32.1 d. 172.31.234.55 e. 192.169.4.519、your organization is using the 192.168.1.0/24 address space. you need 28 subnets. what subnet mask would you use to create these subnets? a. 255.255.255.0 b. 255.255.255.128 c. 255.255.255.192 d. 255.255.255.224 e. 255.255.255.240 f. 255.255.255.248 20、you are given an ip network of 192.168.5.0 and told that you need to separate this network into subnetworks that can support a maximum of 16 hosts per subnet. this will help alleviate congestion on thenetwork. what subnet mask can you use to create the subnets necessary to meet the given criteria? a. 255.0.0.0 b. 255.255.0.0 c. 255.255.255.0d. 255.255.255.224 e. 255.255.255.24021、a client has the ip address 192.168.5.98/27. which of the following addresses are on the same subnet as this host? (choose two.)a. 192.168.5.95 b. 192.168.5.100 c. 192.168.5.128 d. 192.168.5.11022、which of the following ip addresses is not a public ip address that can be routed over the internet?a. 2.3.4.5 b. 11.12.13.14 c. 165.23.224.2 d. 172.31.45.34 e. 203.33.45.2223、 you are given a class b network. what is the default subnet mask assigned to the class b network? a. 255.255.255.255 b. 255.255.0.0 c. 255.224.0.0 d. 0.0.0.024、you are troubleshooting your routers interfaces. for some reason, the ethernet interface will not accept the ip address of 192.168.5.95/27 that youve assigned. which of the following explains the routers refusal to take the ip address? a. class c addresses cannot be assigned to ethernet interfaces. b. the /27 is an invalid mask.c. it is a broadcast address. d. it is a public ip address. e. it is a private ip address.25、you are a network technician at acme, inc. you are required to divide the 172.12.0.0 network into subnets. each subnet must have the capacity of 458 ip addresses. also, according to the requirements, you mustprovide the maximum number of subnets. which subnet mask should you use? a. 255.255.255.254 b. 255.255.254.0 c. 255.255.240.254 d. 255.255.0.026、 what is the subnetwork and broadcast ip address of 192.168.2.37 with the subnet mask of 255.255.255.248? a. 192.168.2.24/192.168.2.31 b. 192.168.2.32/192.168.2.39 c. 192.168.2.40/192.168.2.47d. 192.168.2.48/192.168.2.55 e. 192.168.2.56/192.168.2.6327、one of your co-workers at acme, inc., needs to convert the binary number 11011010 into a decimal.what is the decimal equivalent?a. 218 b. 219 c. 220 d. 221 e. 222 28、one of your co-workers at acme, inc., needs to convert the binary number 01011010 into a decimal.what is the decimal equivalent?a. 75 b. 83 c. 90 d. 97 29、one of your co-workers at acme, inc., needs to convert the binary number 11010110 into a decimal.what is the decimal equivalent?a. 198 b. 214 c. 252 d. 255 30、one of your co-workers at acme, inc., needs to convert the binary number 10110110 into a decimal.what is the decimal equivalent?a. 182 b. 192 c. 202 d. 212 31、you are configuring a subnet for the acme, inc., branch office in beijing. you need to assign ip addresses to hosts in this subnet. you have been given the subnet mask of 255.255.255.224. which of these ip addresses would be valid? (choose three.)a. 15.234.118.63 b. 92.11.178.93 c. 134.178.18.56 d. 192.168.16.87 e. 201.45.116.159 f. 217.63.12.192 32、you are a network technician at acme, inc. you have subnetted the 208.98.112.0 network with a /28mask. your boss asks you how many usable subnetworks and usable host addresses per subnet this will provide. what should you tell her, assuming your router is using ip subnet-zero? a. 62 networks and 2 hosts b. 6 networks and 30 hosts c. 8 networks and 32 hosts d. 16 networks and 16 hosts e. 16 networks and 14 hosts33、y