DOCSLIB.ORG

Nslookupcommand.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Nslookupcommand.Pdf NSLOOKUP has a fairly rich syntax and can be a bit confusing for those who have not worked with DNS a great deal. Therefore, I want to start out by showing you some of the basics. Although NSLOOKUP exists in both UNIX and Windows, there are some differences in the way that it behaves in the two operating systems. For the purposes of this article, I will be using the Windows version. The first thing that you need to understand about NSLOOKUP is that when you use the NSLOOKUP command, it assumes that you are querying a local domain on your private network. You can query an external domain, but NSLOOKUP will try to search for the domain internally first. For example, the brienposey.com domain is external to my network. If I perform an NSLOOKUP against brienposey.com, NSLOOKUP returns the information that’s shown in Figure A. Figure A: This is what happens when NSLOOKUP queries an external domain If you look at the figure, you will see that there are non existent domain error messages for the IP addresses 147.100.100.34 and 147.100.100.5. These are the addresses of my internal DNS servers. Below this information however is the non authoritative answer. This means that my DNS server queried an external DNS server in an effort to resolve the IP address associated with the brienposey.com domain. Now, let’s take a look at what happens when you query an internal domain. One of the local domains on my private network is production.com. If I perform an NSLOOKUP against production.com, I get the results shown in Figure B. Figure B: This is what it looks like when I query an internal domain If you look at the top portion of this screen, you will notice that I’m getting the exact same non-existent domain error messages as I got when I queried an external domain. At first, this may seem puzzling. The reason why I got this error message was because I performed an NSLOOKUP outside of the NSLOOKUP shell. I will talk more about the NSLOOKUP shell in the next section. For now though, you need to know that you can enter the NSLOOKUP command by itself. When you do, you will see the familiar non- existent domain error messages, but you will then be taken to the NSLOOKUP prompt (the > sign). From there you can enter various NSLOOKUP commands. When you are done, you can use the EXIT command to return to the command prompt. The other thing that you should notice about Figure B is the bottom portion of the output. Beneath the reference to production.com is a string of IP addresses. These are the IP addresses of all of the domain controllers within the domain. I should also point out that if multiple IP addresses are assigned to a single server then all of the server’s IP addresses will be displayed by NSLOOKUP. The NSLOOKUP Shell Now that I have shown you how to use the NSLOOKUP command to see the IP address or addresses associated with the domain, let’s do something a little bit more useful. One of the things that you can do with NSLOOKUP is to look up a specific type of DNS record. A good example of this is an MX record. In case you aren’t yet familiar with all of the intricacies of DNS, the MX record points to the organization’s mail server. For example, suppose that someone wanted to send an E- mail message to you, one of the first things that their mail server would have to do is to resolve your domain’s IP address. However, a normal address resolution won’t usually work for this purpose. In Figure A, you saw that when I ran a DNS query against the brienposey.com domain, the domain resolved to the address 24.235.10.4. Keep in mind though, that this is the IP address of the server that hosts my Web site, not the address of my mail server. If someone wanted to send me an E-mail message their E-mail client would have to resolve the IP address of my domain’s mail server. This is where the MX record comes into play. The MX record is a record on a domain’s DNS server that specifies the IP address of the domain’s mail server. As you can see, the MX record is rather important. Suppose however that your domain was having trouble receiving E-mail and you suspected that a DNS server issue was to blame. You could use NSLOOKUP to confirm that the domain does indeed have an MX record and that the MX record is pointed to the correct IP address. Earlier I briefly mentioned that you could work within the NSLOOKUP shell. To troubleshoot an MX record problem, you pretty much have to work within this shell. Therefore, you would start the process by entering the NSLOOKUP command at the command prompt. Once the NSLOOKUP shell is open, you will need to tell NSLOOKUP which DNS server you want to query. To do so, enter the SERVER command, followed by the DNS server’s IP address. You can also enter the server’s fully qualified domain name (assuming that it can be resolved) as an alternative to the server’s IP address. Now that you have specified a DNS server for NSLOOKUP to use, you can query domains without receiving the non-existent domain error messages that you saw earlier (as long as you remain within the NSLOOKUP shell). To do so, you would simply type the domain name that you want to query. For example, if you look at Figure C, you can see where I have specified a particular DNS server and then queried an external and an internal domain. Figure C: The error messages go away if you specify a DNS server Now, let’s get back to the business of looking up a domain’s MX record. To do so, you need to issue a command that tells NSLOOKUP to query based on MX records. The command that you will have to use is: SET QUERY=MX Issuing this command by itself won’t give you any information about the domain’s MX record though. For that you have to actually query the domain by entering the domain name. If you look at Figure D, you will see that I have specified an MX query and then entered the production.com domain name. NSLOOKUP now returns a wealth of information pertaining to my domain’s MX record. Figure D: When an MX query is specified, you can get a wealth of information about your domain’s MX record .
Load more

Recommended publications
  • 1 A) Login to the System B) Use the Appropriate Command to Determine Your Login Shell C) Use the /Etc/Passwd File to Verify the Result of Step B
    CSE ([email protected] II-Sem) EXP-3 1 a) Login to the system b) Use the appropriate command to determine your login shell c) Use the /etc/passwd file to verify the result of step b. d) Use the ‘who’ command and redirect the result to a file called myfile1. Use the more command to see the contents of myfile1. e) Use the date and who commands in sequence (in one line) such that the output of date will display on the screen and the output of who will be redirected to a file called myfile2. Use the more command to check the contents of myfile2. 2 a) Write a “sed” command that deletes the first character in each line in a file. b) Write a “sed” command that deletes the character before the last character in each line in a file. c) Write a “sed” command that swaps the first and second words in each line in a file. a. Log into the system When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as Login : krishnasai password: Then we get log into the commands. bphanikrishna.wordpress.com FOSS-LAB Page 1 of 10 CSE ([email protected] II-Sem) EXP-3 b. use the appropriate command to determine your login shell Syntax: $ echo $SHELL Output: $ echo $SHELL /bin/bash Description:- What is "the shell"? Shell is a program that takes your commands from the keyboard and gives them to the operating system to perform.
    [Show full text]
  • Windows Command Prompt Cheatsheet
    Windows Command Prompt Cheatsheet - Command line interface (as opposed to a GUI - graphical user interface) - Used to execute programs - Commands are small programs that do something useful - There are many commands already included with Windows, but we will use a few. - A filepath is where you are in the filesystem • C: is the C drive • C:\user\Documents is the Documents folder • C:\user\Documents\hello.c is a file in the Documents folder Command What it Does Usage dir Displays a list of a folder’s files dir (shows current folder) and subfolders dir myfolder cd Displays the name of the current cd filepath chdir directory or changes the current chdir filepath folder. cd .. (goes one directory up) md Creates a folder (directory) md folder-name mkdir mkdir folder-name rm Deletes a folder (directory) rm folder-name rmdir rmdir folder-name rm /s folder-name rmdir /s folder-name Note: if the folder isn’t empty, you must add the /s. copy Copies a file from one location to copy filepath-from filepath-to another move Moves file from one folder to move folder1\file.txt folder2\ another ren Changes the name of a file ren file1 file2 rename del Deletes one or more files del filename exit Exits batch script or current exit command control echo Used to display a message or to echo message turn off/on messages in batch scripts type Displays contents of a text file type myfile.txt fc Compares two files and displays fc file1 file2 the difference between them cls Clears the screen cls help Provides more details about help (lists all commands) DOS/Command Prompt help command commands Source: https://technet.microsoft.com/en-us/library/cc754340.aspx.
    [Show full text]
  • Command Line Interface Specification Windows
    Command Line Interface Specification Windows Online Backup Client version 4.3.x 1. Introduction The CloudBackup Command Line Interface (CLI for short) makes it possible to access the CloudBackup Client software from the command line. The following actions are implemented: backup, delete, dir en restore. These actions are described in more detail in the following paragraphs. For all actions applies that a successful action is indicated by means of exit code 0. In all other cases a status code of 1 will be used. 2. Configuration The command line client needs a configuration file. This configuration file may have the same layout as the configuration file for the full CloudBackup client. This configuration file is expected to reside in one of the following folders: CLI installation location or the settings folder in the CLI installation location. The name of the configuration file must be: Settings.xml. Example: if the CLI is installed in C:\Windows\MyBackup\, the configuration file may be in one of the two following locations: C:\Windows\MyBackup\Settings.xml C:\Windows\MyBackup\Settings\Settings.xml If both are present, the first form has precedence. Also the customer needs to edit the CloudBackup.Console.exe.config file which is located in the program file directory and edit the following line: 1 <add key="SettingsFolder" value="%settingsfilelocation%" /> After making these changes the customer can use the CLI instruction to make backups and restore data. 2.1 Configuration Error Handling If an error is found in the configuration file, the command line client will issue an error message describing which value or setting or option is causing the error and terminate with an exit value of 1.
    [Show full text]
  • Don't Trust Traceroute (Completely)
    Don’t Trust Traceroute (Completely) Pietro Marchetta, Valerio Persico, Ethan Katz-Bassett Antonio Pescapé University of Southern California, CA, USA University of Napoli Federico II, Italy [email protected] {pietro.marchetta,valerio.persico,pescape}@unina.it ABSTRACT In this work, we propose a methodology based on the alias resolu- tion process to demonstrate that the IP level view of the route pro- vided by traceroute may be a poor representation of the real router- level route followed by the traffic. More precisely, we show how the traceroute output can lead one to (i) inaccurately reconstruct the route by overestimating the load balancers along the paths toward the destination and (ii) erroneously infer routing changes. Categories and Subject Descriptors C.2.1 [Computer-communication networks]: Network Architec- ture and Design—Network topology (a) Traceroute reports two addresses at the 8-th hop. The common interpretation is that the 7-th hop is splitting the traffic along two Keywords different forwarding paths (case 1); another explanation is that the 8- th hop is an RFC compliant router using multiple interfaces to reply Internet topology; Traceroute; IP alias resolution; IP to Router to the source (case 2). mapping 1 1. INTRODUCTION 0.8 Operators and researchers rely on traceroute to measure routes and they assume that, if traceroute returns different IPs at a given 0.6 hop, it indicates different paths. However, this is not always the case. Although state-of-the-art implementations of traceroute al- 0.4 low to trace all the paths
    [Show full text]
  • Dig, a DNS Query Tool for Windows and Replacement for Nslookup 2008-04-15 15:29
    dig, a DNS query tool for Windows and replacement for nslookup 2008-04-15 15:29 Disclaimer dig (dig for Windows ) (dig is a powerful tool to investigate [digging into] the DNS system) Source of the binary is from ftp.isc.org Manual Page of dig, in the cryptic Unix style, for reference only. (1) Download: Windows 2000 or Windows XP or Windows Vista ( dig version 9.3.2) Create a folder c:\dig Download this dig-files.zip and save it to c:\dig Use winzip or equivalent to extract the files in dig-files.zip to c:\dig Note: If msvcr70.dll already exists in %systemroot%\system32\ , then you can delete c:\dig\msvcr70.dll Note: Included in dig-files.zip is a command line whois, version 4.7.11: The canonical site of the whois source code is http://ftp.debian.org/debian/pool/main/w/whois/ The whois.exe file inside dig-files.zip is compiled using cygwin c++ compiler. (2) Do a file integrity check (why ? Because some virus checkers destroy dll files) Click Start.. Run ... type CMD (a black screen pops up) cd c:\dig sha1 * You should see some SHA1 hashes (in here, SHA1 hash is used as an integrity check, similar to checksums). Compare your hashes with the following table. SHA1 v1.0 [GPLed] by Stephan T. Lavavej, http://stl.caltech.edu 6CA70A2B 11026203 EABD7D65 4ADEFE3D 6C933EDA cygwin1.dll 57487BAE AA0EB284 8557B7CA 54ED9183 EAFC73FA dig.exe 97DBD755 D67A5829 C138A470 8BE7A4F2 6ED0894C host.exe D22E4B89 56E1831F F0F9D076 20EC19BF 171F0C29 libbind9.dll 81588F0B E7D3C6B3 20EDC314 532D9F2D 0A105594 libdns.dll E0BD7187 BBC01003 ABFE7472 E64B68CD 1BDB6BAB libeay32.dll F445362E 728A9027 96EC6871 A79C6307 054974E4 libisc.dll B3255C0E 4808A703 F95C217A 91FFCD69 40E680C9 libisccfg.dll DFBDE4F9 E25FD49A 0846E97F D813D687 6DC94067 liblwres.dll 61B8F573 DB448AE6 351AE347 5C2E7C48 2D81533C msvcr70.dll BDA14B28 7987E168 F359F0C9 DD96866D 04AB189B resolv.conf 1112343A 319C3EEE E44BF261 AE196C96 289C70E2 sha1.exe 21D20035 2A5B64E2 69FEA407 4D78053F 3C7A2738 whois.exe If your hashes are the same as the above table, then your files pass the integrity check.
    [Show full text]
  • AT Command User Guide 80591ST10886A Rev
    LN940 SERIES AT Command User Guide 80591ST10886A Rev. 1.4 – 2018-04-05 ] 7 .201 Mod. 0806 2017-01 Rev.6 01 [ SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE NOTICES LIST While reasonable efforts have been made to assure the accuracy of this document, Telit assumes no liability resulting from any inaccuracies or omissions in this document, or from use of the information obtained herein. The information in this document has been carefully checked and is believed to be reliable. However, no responsibility is assumed for inaccuracies or omissions. Telit reserves the right to make changes to any products described herein and reserves the right to revise this document and to make changes from time to time in content hereof with no obligation to notify any person of revisions or changes. Telit does not assume any liability arising out of the application or use of any product, software, or circuit described herein; neither does it convey license under its patent rights or the rights of others. It is possible that this publication may contain references to, or information about Telit products (machines and programs), programming, or services that are not announced in your country. Such references or information must not be construed to mean that Telit intends to announce such Telit products, programming, or services in your country. COPYRIGHTS This instruction manual and the Telit products described in this instruction manual may be, include or describe copyrighted Telit material, such as computer programs stored in semiconductor memories or other media. Laws in the Italy and other countries preserve for Telit and its licensors certain exclusive rights for copyrighted material, including the exclusive right to copy, reproduce in any form, distribute and make derivative works of the copyrighted material.
    [Show full text]
  • Lab - Observing DNS Resolution (Instructor Version) Instructor Note: Red Font Color Or Gray Highlights Indicate Text That Appears in the Instructor Copy Only
    Lab - Observing DNS Resolution (Instructor Version) Instructor Note: Red font color or Gray highlights indicate text that appears in the instructor copy only. Objectives Part 1: Observe the DNS Conversion of a URL to an IP Address Part 2: Observe DNS Lookup Using the Nslookup Command on a Web Site Part 3: Observe DNS Lookup Using the Nslookup Command on Mail Servers Background / Scenario The Domain Name System (DNS) is invoked when you type a Uniform Resource Locator (URL), such as http://www.cisco.com, into a web browser. The first part of the URL describes which protocol is used. Common protocols are Hypertext Transfer Protocol (HTTP), Hypertext Transfer Protocol over Secure Socket Layer (HTTPS), and File Transfer Protocol (FTP). DNS uses the second part of the URL, which in this example is www.cisco.com. DNS translates the domain name (www.cisco.com) to an IP address to allow the source host to reach the destination host. In this lab, you will observe DNS in action and use the nslookup (name server lookup) command to obtain additional DNS information. Work with a partner to complete this lab. Required Resources 1 PC (Windows 7, Vista, or XP with Internet and command prompt access) Part 1: Observe the DNS Conversion of a URL to an IP Address a. Click the Windows Start button, type cmd into the search field, and press Enter. The command prompt window appears. b. At the command prompt, ping the URL for the Internet Corporation for Assigned Names and Numbers (ICANN) at www.icann.org. ICANN coordinates the DNS, IP addresses, top-level domain name system management, and root server system management functions.
    [Show full text]
  • Your Performance Task Summary Explanation
    Lab Report: 11.2.5 Manage Files Your Performance Your Score: 0 of 3 (0%) Pass Status: Not Passed Elapsed Time: 6 seconds Required Score: 100% Task Summary Actions you were required to perform: In Compress the D:\Graphics folderHide Details Set the Compressed attribute Apply the changes to all folders and files In Hide the D:\Finances folder In Set Read-only on filesHide Details Set read-only on 2017report.xlsx Set read-only on 2018report.xlsx Do not set read-only for the 2019report.xlsx file Explanation In this lab, your task is to complete the following: Compress the D:\Graphics folder and all of its contents. Hide the D:\Finances folder. Make the following files Read-only: D:\Finances\2017report.xlsx D:\Finances\2018report.xlsx Complete this lab as follows: 1. Compress a folder as follows: a. From the taskbar, open File Explorer. b. Maximize the window for easier viewing. c. In the left pane, expand This PC. d. Select Data (D:). e. Right-click Graphics and select Properties. f. On the General tab, select Advanced. g. Select Compress contents to save disk space. h. Click OK. i. Click OK. j. Make sure Apply changes to this folder, subfolders and files is selected. k. Click OK. 2. Hide a folder as follows: a. Right-click Finances and select Properties. b. Select Hidden. c. Click OK. 3. Set files to Read-only as follows: a. Double-click Finances to view its contents. b. Right-click 2017report.xlsx and select Properties. c. Select Read-only. d. Click OK. e.
    [Show full text]
  • Forest Quickstart Guide for Linguists
    Forest Quickstart Guide for Linguists Guido Vanden Wyngaerd [email protected] June 28, 2020 Contents 1 Introduction 1 2 Loading Forest 2 3 Basic Usage 2 4 Adjusting node spacing 4 5 Triangles 7 6 Unlabelled nodes 9 7 Horizontal alignment of terminals 10 8 Arrows 11 9 Highlighting 14 1 Introduction Forest is a package for drawing linguistic (and other) tree diagrams de- veloped by Sašo Živanović. This manual provides a quickstart guide for linguists with just the essential things that you need to get started. More 1 extensive documentation is available from the CTAN-archive. Forest is based on the TikZ package; more information about its commands, in par- ticular those controlling the appearance of the nodes, the arrows, and the highlighting can be found in the TikZ documentation. 2 Loading Forest In your preamble, put \usepackage[linguistics]{forest} The linguistics option makes for nice trees, in which the branches meet above the two nodes that they join; it will also align the example number (provided by linguex) with the top of the tree: (1) CP C IP I VP V NP 3 Basic Usage Forest uses a familiar labelled brackets syntax. The code below will out- put the tree in (1) above (\ex. requires the linguex package and provides the example number): \ex. \begin{forest} [CP[C][IP[I][VP[V][NP]]]] \end{forest} Forest will parse the above code without problem, but you are likely to soon get lost in your labelled brackets with more complicated trees if you write the code this way. The better alternative is to arrange the nodes over multiple lines: 2 \ex.
    [Show full text]
  • Shells and Shell Scripting
    Shells and Shell scripting What is a Shell? • A shell is a command line interpreter that is the interface between the user and the OS. • A “program launcher” of sorts. • The shell: o analyzes each command o determines what actions are to be performed o performs the actions • Example: wc –l file1 > file2 Which shell? • sh – Bourne shell o Most common, other shells are a superset o Good for programming • csh or tcsh – default for command line on CDF o C-like syntax o Best for interactive use. Not good for programming. • bash – default on Linux (Bourne again shell) o Based on sh, with some csh features. • korn – written by David Korn o Based on sh – Some claim best for programming. o Commercial product. Common shell facilities Shell startup When a shell is invoked, it does the following: 1. Read a special startup file (usually in home directory) 2. display prompt and wait for command 3. Ctrl-D on its own line terminates shell, otherwise, goto step 2. Shell startup files used to set shell options, set up environment variables, alias sh – executes .profile if it’s there. ksh – executes .profile if in interactive mode. Executes $ENV (usually $HOME/.kshrc) csh – executes .cshrc if it exists. If a login shell, executes .login bash – executes .bashrc, if a login shell, executes .bash_profile instead Executables vs. built-in commands Most commands you run are other compiled programs. Found in /bin Example: ls – shell locates ls binary in /bin directory and launches it Some are not compiled programs, but built into the shell: cd, echo Input-output redirection prog < infile > outfile ls > outfile 2>&1 # sh stdout and stderr Pipelining commands send the output from one command to the input of the next: ls -l | wc ps –aux | grep reid | sort Before a program is executed, the shell recognizes the special characters such as <, >, |, and rewires the standard input, output, or error file descriptors of the program about to be executed to point to the right files (or the standard input of another program).
    [Show full text]
  • NETSTAT Command
    NETSTAT Command | NETSTAT Command | Use the NETSTAT command to display network status of the local host. | | ┌┐────────────── | 55──NETSTAT─────6─┤ Option ├─┴──┬────────────────────────────────── ┬ ─ ─ ─ ────────────────────────────────────────5% | │┌┐───────────────────── │ | └─(──SELect───6─┤ Select_String ├─┴ ─ ┘ | Option: | ┌┐─COnn────── (1, 2) ──────────────── | ├──┼─────────────────────────── ┼ ─ ──────────────────────────────────────────────────────────────────────────────┤ | ├─ALL───(2)──────────────────── ┤ | ├─ALLConn─────(1, 2) ────────────── ┤ | ├─ARp ipaddress───────────── ┤ | ├─CLients─────────────────── ┤ | ├─DEvlinks────────────────── ┤ | ├─Gate───(3)─────────────────── ┤ | ├─┬─Help─ ┬─ ───────────────── ┤ | │└┘─?──── │ | ├─HOme────────────────────── ┤ | │┌┐─2ð────── │ | ├─Interval─────(1, 2) ─┼───────── ┼─ ┤ | │└┘─seconds─ │ | ├─LEVel───────────────────── ┤ | ├─POOLsize────────────────── ┤ | ├─SOCKets─────────────────── ┤ | ├─TCp serverid───(1) ─────────── ┤ | ├─TELnet───(4)───────────────── ┤ | ├─Up──────────────────────── ┤ | └┘─┤ Command ├───(5)──────────── | Command: | ├──┬─CP cp_command───(6) ─ ┬ ────────────────────────────────────────────────────────────────────────────────────────┤ | ├─DELarp ipaddress─ ┤ | ├─DRop conn_num──── ┤ | └─RESETPool──────── ┘ | Select_String: | ├─ ─┬─ipaddress────(3) ┬ ─ ───────────────────────────────────────────────────────────────────────────────────────────┤ | ├─ldev_num─────(4) ┤ | └─userid────(2) ─── ┘ | Notes: | 1 Only ALLCON, CONN and TCP are valid with INTERVAL. | 2 The userid
    [Show full text]
  • 1. Run Nslookup to Obtain the IP Address of a Web Server in Europe
    1. Run nslookup to obtain the IP address of a Web server in Europe. frigate:Desktop drb$ nslookup home.web.cern.ch Server: 130.215.32.18 Address: 130.215.32.18#53 Non-authoritative answer: home.web.cern.ch canonical name = drupalprod.cern.ch. Name: drupalprod.cern.ch Address: 137.138.76.28 Note that the #53 denotes the DNS service is running on port 53. 2. Run nslookup to determine the authoritative DNS servers for a university in Asia. frigate:Desktop drb$ nslookup -type=NS tsinghua.edu.cn Server: 130.215.32.18 Address: 130.215.32.18#53 Non-authoritative answer: tsinghua.edu.cn nameserver = dns2.tsinghua.edu.cn. tsinghua.edu.cn nameserver = dns.tsinghua.edu.cn. tsinghua.edu.cn nameserver = dns2.edu.cn. tsinghua.edu.cn nameserver = ns2.cuhk.edu.hk. Authoritative answers can be found from: dns2.tsinghua.edu.cn internet address = 166.111.8.31 ns2.cuhk.edu.hk internet address = 137.189.6.21 ns2.cuhk.edu.hk has AAAA address 2405:3000:3:6::15 dns2.edu.cn internet address = 202.112.0.13 dns.tsinghua.edu.cn internet address = 166.111.8.30 Note that there can be multiple authoritative servers. The response we got back was from a cached record. To confirm the authoritative DNS servers, we perform the same DNS query of one of the servers that can provide authoritative answers. frigate:Desktop drb$ nslookup -type=NS tsinghua.edu.cn dns.tsinghua.edu.cn Server: dns.tsinghua.edu.cn Address: 166.111.8.30#53 tsinghua.edu.cn nameserver = dns2.edu.cn.
    [Show full text]