计网实验-http

回答以下问题时，需要原GET和响应消息截图，在图中标示答案。并文字描述答案。

1. Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the server running?

通过GET请求的描述，可以得知浏览器使用HTTP 1.1。

从服务器返回可以得知，对方也使用HTTP 1.1。

1. What languages (if any) does your browser indicate that it can accept to the server?

从图中Accept-Language可以得知，

接受语言种类有zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2，即中文（大陆）、英语（威尔士、美式）。

1. What is the IP address of your computer? Of the gaia.cs.umass.edu server?

本机ip：10.135.1.207

gaia.cs.umass.edu ip：128.119.245.12

1. What is the status code returned from the server to your browser?

返回状态码为200。

1. When was the HTML file that you are retrieving last modified at the server?

Wed, 22 Mar 2023 05:59:02 GMT

1. How many bytes of content are being returned to your browser?

128bytes。

1. By inspecting the raw data in the packet content window, do you see any headers within the data that are not displayed in the packet-listing window? If so, name one.

没有观察到。

1. Inspect the contents of the first HTTP GET request from your browser to the server. Do you see an “IF-MODIFIED-SINCE” line in the HTTP GET?

没有。

1. 

   Inspect the contents of the server response. Did the server explicitly return the contents of the file? How can you tell?

的确显式返回了。

如上图所示，返回了文件内容。

1. Now inspect the contents of the second HTTP GET request from your browser to the server. Do you see an “IF-MODIFIED-SINCE:” line in the HTTP GET? If so, what information follows the “IF-MODIFIED-SINCE:” header?

注意到了。

其后的是一串时间信息，它与先前GET请求的LAST-MODIFIED: 后的内容相同

1. What is the HTTP status code and phrase returned from the server in response to this second HTTP GET? Did the server explicitly return the contents of the file? Explain.

304 Not Modified

注意到HTTP response没有显式返回文件。

因为先前的GET之后，浏览器已经获取过HTTP-wireshark-file2.html，并在本地缓存它。第二次GET请求向服务器通过IF-MODIFIED-SINCE确认文件在第一次GET之后未被更改，服务器返回Not Modified响应，没有显式返回文件内容，于是浏览器使用了缓存网页。

1. How many HTTP GET request messages did your browser send? Which packet number in the trace contains the GET message for the Bill or Rights?

1个GET请求。

如图，3132号。

1. Which packet number in the trace contains the status code and phrase associated with the response to the HTTP GET request?

3181号。

1. What is the status code and phrase in the response?

200 OK

1. How many data-containing TCP segments were needed to carry the single HTTP response and the text of the Bill of Rights?

2个。如上图3181、3182示。

1. How many HTTP GET request messages did your browser send? To which Internet addresses were these GET requests sent?

发送了3个HTTP GET请求消息，2个发往128.119.245.12，一个发往178.79.137.164。

1. 

   Can you tell whether your browser downloaded the two images serially, or whether they were downloaded from the two web sites in parallel? Explain.

串行的。

可以注意到这几个数据包之间的先后顺序：

请求图片1（328号）-返回图片1（430号）-请求图片2（618号）-返回图片2（664号）

1. What is the server’s response (status code and phrase) in response to the initial HTTP GET message from your browser?

401 Unauthorized

初次：

第二次：

1. When your browser’s sends the HTTP GET message for the second time, what new field is included in the HTTP GET message?

authorization