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I.~ . . .” tli&lighs of DNS Pase I of2

NJIT CPE Webmaster 20001 Domain Name System Highlights: The Internet Domain Names System is a Hierarchical System that will resolve host names to IP address.

RoOt SERVERS

Step 3. Root server provides Dom record and address of nameserver the whatttkcom domain for the Ioc Nameserver The local “amesewel Step 2 Local then requests the IP resolution from Nameserver attempts the nameserver hosting the domain to resolve IP address. Does not have k in I’s records so it querries the foot server for the nalneserverthat has DNS record of that the domain record for whattis.com responds to the

www.whatffis.com 204,, 4, .22g, other.COM nameserver

www.whptiio.com PC USER Step 5. Onccthe address has been resolved the webserver ca” respond 10 the request for the web pages assccided v&h the URL of www.whatiis.com

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The above ilhrstration shows in a general way bow the Domain Name system functions.

1. A request is made for a particular URL by a host PC. This could be a home user looking for a website known as uwwwhatitiscom 2. The TCP/lP setings on that PC will Srst check it’s local hosts tiles for resolution. Following that it will query the DNS servers that have been entered into the TCPKP configuration. 3. lf the local DNS server is not hosting the domain records for that domain i.e whatitiscom it will query the .com root server to tind out the ip address of the DNS setver that has the domain record for that particular domain. The .com rootserver provides the ip address of the DNS server that has the necessary domain record. The local nameserver then requests the IP resolution from the appropriate nameserver. 4. The nameserver that has the domain record for that domain can respond with the Ml resolution for the URL wuw.whatitis.com to the local nameserver. The local nameserver then provides the IF’ address to the hosr that origonally made the request. 5. Finally the resolved URL can be found and the webserver will respond to requests from the host / client PC requesting the web pages to be downloaded.

http:Ncpe2.njit.edu/portfolio/tjudge/Lessonl/DNS_highlights.htm 512 l/O0 Example of A Wan interconnect Functional 1. Judge 4/3/2[100

172~16.80.20 Network to Remote 1

Note: Bdh routers must have route address in table to accomodate Internal Network. 10.4.25.0 255.255.255.0 $j_Remote IGateway 10.254.18.2 Remote 2 Gateway 10.4.28.2 Cism Router 1 Cisco Router 2 10.4.28.1 10.2S4.18.1 255.255.255.0 255.255.255.0

10.4.25.3 Pa&c- I Page I of2

On Line Communily N&vvorks.cum Inc. IP Services Functional ISP Key Nodes

ISDN Pipe 50

swlched ISDN

ISDN Pipe 50 CUST 2 204.141.175.3 Corm Server Subn Net204.111175~ Mask 255255.255. 8 Port Hub Dialup Pool 204241.175. I 56K x 24 I-WI GW.NJLAKES.i’!El u. DNS SERVER 1 -- 204.141.175.10 iti NSZ.NJLAKES.NET DNS smvm 2 204.141 .I7515

T-l CSUlDSU Router P Expws UprbsamlP Service 204.141 d 75.1 Mas Bca:

USR TO!wi2 POti ’ T-l CSUlDSU Rouler

IP Express Downstream IP Service D FRAME RELAY CUSTOMER

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Example of A Wan interconnect Functional T. Judge 4fX2000

Public Swttched Networkto Remote

Both rorders must have route address in table to, accomodate Internal Network. 10.4.25:o

Remde IGateway 10.254.18.2 r> Rarnle2:::::;~:0.4.28,2 Ciico Router 2 10.4.28.1 10.25418.1 255.255.255.0 255.255255.0 I

1 5poltTHub NTNIC

Local NT Server MuLthomed NT server wtth Microsoft

Local DHCP Host

1 W&muse Hub I

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Orders

TSA2P002 Packing List

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Intro to Lans Lesson 6

Introduction to Unix type systems and Networks

History of Unix Highlights:

. 1972 10 computers existed running UNIX . developed by Bell Labs in 1972 by Dennis Ritchie and Ken Thompson . developed using C as the development language . 1974-1979 Unix was mainly a research product used in Universities . Origionall owned by AT&T who gave it away due to government restrictions against the monoply it had. That way Microsoft could make a monoply later on in the 90’s . 1974 University of Berkley California began to develop BSD Unix . Bill Joy t?om BSD developed the Sun Microsystem Spare Workstation which is an extended version of BSD Unix . Other Flavors of Unix include 1BM;s AIX, Hewlett Packard’s HP-UX, DEC Ultrix . Microsoft released Xenix in 1980. First Unix for PC . Santa Cruz Operation developed SC0 Unix . Unixware was owned by Novell until recently it was sold . Novell bought Unix as part of it’s purchase of Unix system Labs . 1991 Linux development began by Linus Torvalds, University of Helsinki . 1992 first bug free release of Linux Linux is copyrighted by the GNU /GPU General Public License. You can resel it but you must include the source code. . Absolutely no warrenties come with Linux

._--_____ IMPORTANT UNIX FACTS

It is case sensitive print is not the same as Print at the command line Note the direction of the “1” slash symbol for designating paths to files and directories, It is a 32 bit operating system Long file names and extensions are OK Various operating shells for Unix include:

Sh the Boume shell origional shell for Unix dates back to 1979 Ksh Kom Shell developed by David Kom added feature from cshell Csh the C shell developed by Bill Joy (sun microsystems) job history and aliases Bash Boume Again Shell developed by the first free software foundation

To find out what type of shell you are running you can type echo SSHELL

Xfree86 the free Windows for Unix

. Xfree86 is the distribution of X-Windows terminal for Unix (Linux)

. Install and run XFS6Setup to configure system

. Start using openwin FILE SYSTEMS

. UNIX -everything is mounted as a logical directory NO logical drive letters like DOS / Windows . Mount command: mount . Example: mount /de&ad1 kome . The above will mount the root of that device hdal as /home in the existing filesystem

Some Handy File system commands:

df disk free shows available disk space on system Is comparable to the dir command Is -1 with details pwd show the current directory we are in cp copy file mv move files mkdir make directory rm remove or delete directory or file rm-r would be recursive (comparable to deltree in dos

Symbolic links (Windows shortcuts stole this from Unix) This will create a link of a file or directory from one location to another.

Command = In

Example In /home/tom/testtile /homeikathy/testfile

NFS Page 4 of 6

Remote mount of file systems

Example of command: mount -t nfs : / -- mounted to this directory

Permissions are set in /etc/exports

IE:

/t&tom gives read write to remote host

/t&tom gives read only permission to remote host

FILE SYSTEM PERMISSIONS IN UNIX

Permissions are basic:

. r - read permissions s w - write permissions . x - execute permissions

These permissions are tiered into 3 groups:

. Owner . Group . Everyone

For example the tile listed below shows the following -rw-r--r-- testfile root root 30 Nov 21:07:59

The permission are read and write for the owner and read for the group and read for the world chmod is the command to change permissions on a file or folder chmod

-tw-rw-r-- testfile root root 30 Nov 2 1:07: 59

There is also a shortcut for the &mod using numbers:

. 000 no permissions . 001 other execute . 002 other write . 004 other read . 010 group execute . 020 group write . 040 group read . 100 user execute . 200 user write . 400 user read

You can add the numbers together to set bulk permissions at once:

IE chmod 777 testfile gives everyone full permissions Pagebof6

chmod 644 testfile gives owner read and write, group read and other read

CHANGING OWNER OR GROUP

chown changes owner chown testfile kathy would change the ownership iof that file to kathy chgrp testfile users would change the group ownership of the file to the group users.

klnix Networking Highlights:

The native protocol for Unix Networking has always been TCP/IP Unix machnes communicate using the TCP/IP suite of protocols Thers is a utility available known as Samba which will allow a Unix PC to appear in the Microsoft Network Neighborhood and exchange data as an SMB server. SMB - Server Message Blocks - the microsoft standard supporting NetBIOS file share names. In Unix Network Shares are Mounted to the existing Hosts file system at a mount point as a directory. There is no logical drive letter mapping as in Novell or Microsoft Networking.

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