1、1陕西师范大学 计算机网络 实验报告实验四 DNS一、实验目的1.熟悉并掌握 wireshark 的操作。 2分析 DNS协议。二、实验器材1.PC机电脑一台。2下载 wireshark软件并安装三、实验内容及问题回答1.练习使用 nslookup 程序发送 DNS 查询1. Run nslookup to obtain the IP address of a Web server in Asia.2. Run nslookup to determine the authoritative DNS servers for a university inEurope.3. Run nslooku
2、p so that one of the DNS servers obtained in Question 2 is queried forthe mail servers for Yahoo! Mail德国德累斯顿工业大学22.练习使用 ipconfig（1）ipconfig/all（2）.Ipconfig/displaydns3（3）.ipconfig/flushdns3. Tracing DNS with Wireshark实验 1 过程：1使用 ipconfig 清空 DNS 缓冲存储；2清空浏览器的缓存；3启动 Wireshark，在 filter 中输入“ip.addr=10.2.
3、136.26”;4开始抓包；5访问 http:/www.ietf.org；6 页面打开后，停止抓包。4. Locate the DNS query and response messages. Are they sent over UDP or TCP?清除缓存4答：用的是 UDP5. What is the destination port for the DNS query message? What is the source portof DNS response message?答：Src Port :domain(53), Dst Port: domain(53)6. To wha
4、t IP address is the DNS query message sent? Use ipconfig to determine theIP address of your local DNS server. Are these two IP addresses the same?答：Destination:202.117.1442(202.117.144.2) 与用本地 DNS 服务器的 IP 地址相同。7. Examine the DNS query message. What “Type” of DNS query is it? Does thequery message co
5、ntain any “answers”?答：TYPE 为 A,没有应答，8. Examine the DNS response message. How many “answers” are provided? Whatdoes each of these answers contain?Ip 地址：202.117.144.2Ip 地址：202.117.144.2没有应答类型 type A1 个应答5答：有一个应答。应答的内容包括：Name 、Type 、Class、Time to live、Data、 Addr.9. Consider the subsequent TCP SYN packe
6、t sent by your host. Does the destinationIP address of the SYN packet correspond to any of the IP addresses provided inthe DNS response message?答：不一致10. This web page contains images. Before retrieving each image, does your hostissue new DNS queries?答：没有。实验 2 过程：1. 开始抓包；2. 使用 nslookup 获取 www.mit.edu
7、 的地址。3. 停止抓包。实验结果：应答包含的内容611. What is the destination port for the DNS query message? What is the source portof DNS response message?答：Destination Port：domain(53) Source Port: domain(53)12. To what IP address is the DNS query message sent? Is this the IP address of yourdefault local DNS server?7答：是。
8、13. Examine the DNS query message. What “Type” of DNS query is it? Does thequery message contain any “answers”?答：类型为A；没有应答。14. Examine the DNS response message. How many “answers” are provided? Whatdoes each of these answers contain?本地 DNS服务器 IP地址没有应答类型 typeA8答：有一个应答。应答的内容包括：Name 、Type 、Class、Time t
9、o live、Data、 Addr.实验 3. 重复实验 2 的操作，使用 nslookup 时限定 Type 为 NS。16. To what IP address is the DNS query message sent? Is this the IP address of yourdefault local DNS server?一个应答应答包含的内容9答：相同。17. Examine the DNS query message. What “Type” of DNS query is it? Does thequery message contain any “answers”?答：
10、 ；没有应答。18. Examine the DNS response message. What MIT name servers does the responsemessage provide? Does this response message also provide the IP addresses of theMIT name servers?答：提供3个name servers,没有提供IP地址。实验 4. 重复实验 3 的操作，但是在命令行输入Nslookup www.aiit.orkr bitsy.mit.edu实验结果：本地 DNS 服务器 IP 地址1020. To
11、what IP address is the DNS query message sent? Is this the IP address of yourdefault local DNS server? If not, what does the IP address correspond to?答：18.72.0.3。不是。与指定的服务器的IP地址一致。21. Examine the DNS query message. What “Type” of DNS query is it? Does thequery message contain any “answers”?22. Examine the DNS response message. How many “answers” are provided? Whatdoes each of these answers contain?本地 DNS服务器 IP地址类型为 A没有应答一个回答内容11答：一个回答。包括Name ，Type，Class， Time to live，Data length，Addr 。
