mạng máy tính tổng hợp kết quả thực hành về dns và http

Does the query message contain any “answers”?. Does the query message contain any “answers”?. similar this image is DNS response massage, source post of DNS response is 53, same the dest

KHOA CÔNG NGHỆ THÔNG TIN – KHOA ĐIỆN

MỞ ĐẦU Trong thời đạ ủi c a mạng máy tính ngày nay, DNS (Domain Name System) và HTTP (Hypertext Transfer Protocol) đóng vai trò không thể phủ nhận trong vi c k t nệ ế ối và truy cập vào các dịch v ụ trên Internet DNS là hệ thống giúp dịch các tên miền thành địa chỉ IP, giúp cho việc giao tiếp giữa các thiết b ị trên mạng tr ở nên dễ dàng hơn Trong khi đó, HTTP là giao thức phổ biến nhất được s dử ụng để truy n t i d ề ả ữ liệu trên World Wide Web

Điều quan trọng là hiểu rõ cách hoạt động của DNS và HTTP không chỉ giúp chúng ta hiểu sâu hơn về cơ chế hoạt động của Internet, mà còn cung cấp cơ sở cho vi c triệ ển khai và quản lý hệ thống mạng hiệu qu Trong ảbáo cáo này, chúng tôi sẽ trình bày kết quả thực hành của chúng tôi về DNS và HTTP, từ việc cấu hình đến giám sát và phân tích hiệu suất Chúng tôi hy vọng r ng vi c chia s kinh nghi m cằ ệ ẻ ệ ủa chúng tôi sẽ mang lại cái nhìn toàn diện hơn về hai giao thức quan trọng này và ảnh hưởng của chúng đối với mạng máy tính hiện đại

MỤC LỤC

M Ở ĐẦ 1 U M C L C ỤỤ 2 DANH MỤC HÌNH ẢNH 4

DNS 5 1 Run nslookup to obtain the IP address of a Web server in Asia What is the IP address of that server 5 2.Run nslookup to determine the authoritative DNS servers for a university in Europe 5 3.Run nslookup so that one of the DNS servers obtained in Question 2 is queried for the mail servers for Yahoo! mail What is its IP address? 6 4 Locate the DNS query and response messages Are then sent over UDP or TCP? 6 5 What is the destination port for the DNS query message? What is the source port of DNS response message? 7 6 To what IP address is the DNS query message sent? Use ipconfig to determine the IP address of your local DNS server Are these two IP addresses the same? 8 7 Examine the DNS query message What “Type” of DNS query is it?

Does the query message contain any “answers”? 9 8 Examine the DNS response message How many “answers” are provided? What do each of these answers contain? 10 9 Consider the subsequent TCP SYN packet sent by your host Does

12 To what IP address is the DNS query message sent? Is this the IP

address of your default local DNS server? 12

13 Examine the DNS query message What “Type” of DNS query is it? Does the query message contain any “answers”? 12

14 Examine the DNS response message How many “answers” are provided? What do each of these answers contain? 13

19 Provide a screenshot 16

20 To what IP address is the DNS query message sent? Is this the IP address of your default local DNS server? If not, what does the IP address correspond to? 16

21 Examine the DNS query message What “Type” of DNS query is it? Does the query message contain any “answers”? 17

22 Examine the DNS response message How many “answers” are provided? What does each of these answers contain? 17

23 Provide a screenshot 18

HTTP 19

1 The Basic HTTP GET/response interaction 19

2 The HTTP CONDITIONAL GET/response interaction 20

3 Retrieving Long Documents 22

4 HTML Documents with Embedded Objects 23

5 HTTP Authentication 24

3.Run nslookup so that one of the DNS servers obtained in Question 2 is queried for the mail servers for Yahoo! mail What is its IP

5 What is the destination port for the DNS query message? What is the source port of DNS response message?

From this image destination port for the DNS query is 53 similar this image is DNS response massage, source post of DNS response is 53, same the destination port of DNS query

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6 To what IP address is the DNS query message sent? Use ipconfig to determine the IP address of your local DNS server Are these two IP addresses the same?

IP address that the DNS query message sent: 192.168.205.151

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the IP address of my local DNS server:192.168.205.151

these two IP addresses are same

7 Examine the DNS query message What “Type” of DNS query is it? Does the query message contain any “answers”?

“Type” of DNS query is A, and the query message doesn’t contain any “answers”

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8 Examine the DNS response message How many “answers” are

provided? What do each of these answers contain?

The DNS response have 2 “answers”, What each of these answers contain are showing in the image

9 Consider the subsequent TCP SYN packet sent by your host Does the destination IP address of the SYN packet correspond to any of the IP addresses provided in the DNS response message?

The destination of the SYN packet is 104.16.44.99, the same address that was provided in the DNS response message as the type “A” address of the webpage

10 This web page contains images Before retrieving each image, does your host issue new DNS queries?

Yes, my host did issue new DNS queries before the images were retrieved For example, one such query was for an image from open-stand.org The image corresponding to the page was not returned until this query was made

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11 What is the destination port for the DNS query message? What is the source port of DNS response message?

destination port for the DNS query message: 53

source port of DNS response message: 53

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12 To what IP address is the DNS query message sent? Is this the IP address of your default local DNS server?

IP address is the DNS query message sent is: 192.168.205.151 and this IP address is my default local DNS server

13 Examine the DNS query message What “Type” of DNS query is it? Does the query message contain any “answers”?

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14 Examine the DNS response message How many “answers” are

provided? What do each of these answers contain?

16 To what IP address is the DNS query message sent? Is this the IP address of your default local DNS server?

IP address is the DNS query message sent is: 192.168.205.151 and this IP address is my default local DNS server

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17 Examine the DNS query message What “Type” of DNS query is it? Does the query message contain any “answers”?

“Type” of DNS query is NS, doesn’t have any “answer”

18 Examine the DNS response message What MIT nameservers does the response message provide? Does this response message also provide the IP addresses of the MIT namesers?

MIT Name: dscb.akamaiedge.net, this response message also provide the IP addresses of the MIT namesers

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19 Provide a screenshot

20 To what IP address is the DNS query message sent? Is this the IP address of your default local DNS server? If not, what does the IP address correspond to?

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21 Examine the DNS query message What “Type” of DNS query is it?

Does the query message contain any “answers”?

“Type” of DNS query is A, the query message doesn’t contain any “answers”

22 Examine the DNS response message How many “answers” are

provided? What does each of these answers contain?

Server does sent any DNS response message

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23 Provide a screenshot

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HTTP

1 The Basic HTTP GET/response interaction

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

The Browser is running HTTP 1.1

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

It indicates that it can accept an vi-VN language

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

The IP of my computer is 192.168.1.74 and the server IP is 128.119.245.12

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

200 OK is the status code returned to the browser

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

It was last modified on Sat, 16 Mar 2024 12:58:36 GMT

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

128 bytes is being returned to the browser

2 The HTTP CONDITIONAL GET/response interaction

8 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?

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

Yes, the server did return the contents of the file as there is a based text data” line and under it is the text

“Line-10 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?

I see an “IF-MODIFIED-SINCE” line in the HTTP GET IF-MODIFIED-SINCE: Sat, 16 Mar 2024 05:59:02 GMT

11 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?

The status code is 304 Not Modified and this time it did not return the contents of the file The reason is that since the file was not modified there is no new content that needs to be passed and so there is no need to download the file again

3 Retrieving Long Documents

12 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?

Just one request message was sent by the browser

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

There were 4 segments needed to carry the HTTP response The sizes for the segments are: 1452 bytes, 1452 bytes, 1452 bytes, and 505 bytes

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14 What is the status code and phrase in the response?

The status code is 200 OK

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

It takes 4 TCP segments to contain the entire HTTP response and The Bill of Rights content

4 HTML Documents with Embedded Objects

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

Three requests message was sent by the browser The GET request is sent to the address "128.119.245.12" respectively; "165.193.123.218" ; "134.241.6.82".One each to each for each of the following: The initial page, the Pearson logo, and the cover of the Pearson book, 8th Edition

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

The browser downloaded the two images sequentially Because the first image was requested and sent before the second image was requested by the browser If they run in parallel then both files will be requested and will be returned in the same amount of time In this case, the second image is requested only after the first image returns

5 HTTP Authentication

18 What is the server’s response (status code and phrase) in response to

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19 When your browser sends the HTTP GET message for the second time, what new field is included in the HTTP GET message?