1 Review For Exam 2 (Week 8, Wednesday 3/1/2006) © Abdou Illia, Spring 2006

2 IP Subnetting

3 Structure of IP addresses Network Part (n) Local Part (h) Class Annnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh – Class Bnnnnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh – Class Cnnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh – Sgmt. partHost part

4 Reserved IP addresses ClassRange A – B – C – IP addresses reserved for private use. AddressUse Example: Local broadcast to LAN computers Broadcast to network / Loopback address (for self addressing) Prohibited x.xAutomatic Private IP Addressing Special IP addresses.

5 Structure of IP addresses The division between Network part, Segment part, and Host part is determined by a computer or a router by using a network mask. Network Part Segment Part Host Part

6 Network mask A 32 bit number, just like an IP address, where all bits in the Network Part and the Segment Part are set to 1, and all bits in the Host Part are set to 0. Example: (or in decimal notation) Computers use Network mask, along with the IP address, to determine whether or not a destination IP address is on the same logical network.

7 The ADDing technique Do the following three Class C IP addresses belong to the same network? , and IP: Mask: Network: /24 IP: Mask: Network: /24 IP: Mask: Network: / Network 1: /24, i.e network starting at with network mask Network 2: /24, i.e network starting at with network mask

8 Two Virtual LANs Switch

9 Two interconnected LANs

10 Subnetting a class C network Suppose the /24 network You want to divide that network into two segments  You can decide to use the first bit of the fourth octet as dividing point between your network segments. So, your network mask would be: And you will have about 2 7 = 128 hosts in each segment Segment 1: to Segment 2: to How to create the two segments using the ADDing technique?

11 Subnetting a class C network IP: Mask: Network: / IP: Mask: Network: / Segment 1: to

12 Subnetting a class C network IP: Mask: Network: / IP: Mask: Network: / Segment 2: to

13 Question 1 Network A is IP network /24 (i.e a Class C network with a default 24-bit mask). Using the IP Subnet Calculator, determine the maximum number of hosts (computers) in each of the Network A’s subnets assuming that there are two subnets. You answer: ________. Using the IP Subnet Calculator, determine the maximum number of subnets for a Class B network assuming that the four first bits of the third octet in each IP address are used as subnet bits. Your answer: _____. What is the maximum number of computers for each subnet? Your answer: ______.

14 Question 2 Consider the /24 network. What is the maximum number of hosts in that network? Suppose that the /24 network is segmented, and became /25 What is the maximum number of hosts in in each subnet? Would IP address be in the same subnet as IP address ? Consider the /24 network. You want to segment that network in order to create 4 subnets. What would be the four (4) address ranges? What would your subnet mask be?

15 Disk Management

16 Basic disk A physical disk that can be accessed by MS-DOS and all Windows-based operating systems. Basic disks can contain up to 4 primary partitions, or 3 primary partitions and an extended partition with multiple logical drives. Primary partition 1 Primary partition 2 Primary partition 3 Primary partition 4 Primary partition 1 Primary partition 2 Primary partition 3 Extended partition A primary partition is a portion of a physical disk that functions as though it were a physically separate disk. You create a primary partition, then you format it with a file system (FAT or NTFS,) and then assign a drive letter to it (e.g. C:, D:, F:, etc.) A primary partition can start the OS (contain the boot files) A special kind of partition used to create one or more logical drives After you create a logical drive, you format it and assign it a drive letter (e.g. G:, H:, etc.) An extended partition cannot start the OS. Note: With GPT (GUID partition table) disk-partitioning scheme that is used by the Extensible Firmware Interface (EFI) in Itanium-based computers, we can create up to 128 (primary) partitions per disk

17 Dynamic disk With Win 2000, you can convert a Basic disk to a Dynamic disk With a dynamic disk, you can create an unlimited number of volumes Volume C: Volume D: Volume E: Configuration partition (1 MB) Etc…. Dynamic disks provide features that basic disks do not, such as:  the ability to create volumes that span multiple disks (spanned and striped volumes), and  the ability to create fault tolerant volumes (mirrored and RAID-5 volumes). A spanned volume is a dynamic volume consisting of disk space on more than one physical disk. Spanned volumes are not fault tolerant and cannot be mirrored. A striped volume is a dynamic volume that stores data in stripes on two or more physical disks. Striped volumes do not provide fault tolerance. If a disk in a striped volume fails, the data in the entire volume is lost. Special partition automatically created to store the configuration of the disk

18 Mirrored volume A fault-tolerant volume that duplicates data on two physical disks If one of the physical disks fails, the data on the failed disk becomes unavailable, but the system continues to operate. You can create mirrored volumes only on dynamic disks. file1file3file2file4 file1file3file2file4

19 RAID-5 volume A fault-tolerant volume with data and parity striped intermittently across three or more physical disks. Parity is a calculated value that is used to reconstruct data after a failure If a portion of a physical disk fails, Windows recreates the data that was on the failed portion from the remaining data and parity. You can create RAID-5 volumes only on dynamic disks, Disk 1 Disk 2 Disk 3 Disk 4 Disk 5 ParityData ParityData ParityData ParityData Parity

20 Converting Basic disk to Dynamic disk For the conversion to succeed:  any disks to be converted must contain at least 1 MB of space for the dynamic disk database.  Note: Windows 2000 automatically reserve this space when creating partitions or volumes on a disk (This space may exist even if it is not visible in Disk Management.) Once converted:  a dynamic disk will not contain primary partitions or logical drives  a dynamic disk cannot be accessed by MS-DOS, Windows 95, Windows 98, Windows Millennium Edition, Windows NT, or Windows XP Home Edition When you convert a basic disk to a dynamic disk:  any existing partitions or logical drives on the basic disk become simple volumes on the dynamic disk.

21 Converting Dynamic disk to Basic disk The disk must be empty before you can change it back to a basic disk Converting a Dynamic disk to Basic disk causes all data to be lost If you want to keep your data, back it up or move it to another storage device You must remove all volumes from the dynamic disk

22 Limitations of Dynamic disk Dynamic disks are not supported on:  Portable computers  Removable disks  Detachable disks that use Universal Serial Bus (USB) or IEEE 1394 (also called FireWire) interfaces,  Disks connected to shared SCSI buses Dynamic volumes (and the data they contain) cannot be accessed by, or created on:  Computers running MS-DOS, Windows 95, Windows 98, Windows Millennium Edition, Windows NT 4.0, or Windows XP Home Edition

23 File system security

24 Shared Folders To see all shared folders on a computer: 1)Click Start. Then click Run 2)Type \\ComputerName (where ComputerName is a valid network computer name like SRVDC18) 3)Click OK. To share a folder on a computer: 1)Open My Computer (Right-click/Open) 2)Select a disk, then the folder to share 3)Right-click the selected folder 4)Click Properties 5)Click the Sharing tab 6)Check Share this folder 7)Click Apply, and then OK. Requirements for creating a shared folder:  Any supported File system (FAT, NTFS)  If server in a domain, you must be Administrator or Server Operator  If server in a workgroup, you must be Administrator or Power user  If Client computer running a Workstation OS, you must be Administrator or Power user Note: Users that are granted the Create Permanent Shared Objects right can also create shared folders on the computer where the right is assigned OR 1)Open Computer Management 2)In the console tree, double-click Shared Folders 3)Click Shares

25 Shared Folder Permissions Multiple Permissions (The Combination Rule)  If a user is assigned a permission for a Shared folder and  If the use user belongs to a group to which a different permission is assigned,  Then the user’s effective permissions are the combination of the user and group permissions Deny overrides Allow  If you deny a shared folder permission to a user and  If you allow the same permission to a group the user belongs to  Then the user will not have that permission. Copying or Moving Shared folders  If you copy a Shared folder, the original folder is shared but not the copy  If you move a Shared folder, it is no longer shared.

26 NTFS Permissions Multiple Permissions  NTFS file permissions take priority over NTFS folder permissions A user can always access files for which he/she has permissions using UNC. E.g. \\SRVDC16\Data\file1.txt  Denying a permission for a user blocks that permission, even if the permission is granted to a group the user belongs to. Permission Inheritance  By default, permissions assigned for the parent folder are inherited at subfolder and file level  To prevent automatic inheritance, explicit permissions assignments must be done at subfolder and/or file levels. Copying or Moving Files and Folders  When a file/folder is moved within an NTFS partition, it retains its permissions  When a file/folder is copied to another NTFS partition, it inherits the permissions of the destination folder (Golden rule)  When a file/folder is copied to a FAT partition, it loses its NTFS permissions

27 Shares & permissions Sharing folders/files Setting permissions FATNTFSFATNTFS Folders/Subfolders YES YES (but limited) YES Files NO YES

28 Exercise 1 You shared a folder on a Windows 2000 Server computer for users in your company’s London office. You place several subfolders in the London Folder as shown in the exhibit.

29 Exercise 1 (Cont.) The Marketing-2 folder is compressed. You want to delete Marketing-2, but you want to keep all the files that are currently in the folder. You plan to copy all the files in Marketting-2 into the Marketing folder before deleting Marketing-2. You want these files to remain compressed. However, you do not want to compress any existing files in Marketing or compress any other new files added to the Marketing. What should you do before you delete Marketing-2? A. Copy all the files from Marketing-2 to Marketing. B. Move all the files from Marketing-2 to Marketing. C. Compress Marketing and then copy all the files from Marketing-2 to Marketing. D. Compress Marketing and then move all the files from Marketing-2 to Marketing.

30 Distributed File System, Disk Quotas

31 Dfs: Scenario 1 Problems if there are dozens of servers Server 2 \Data Server 3 \Sales Server 1 \Install Server 4 \Policy Dfs not used  Four shared folders on 4 different servers  User need to know servers and folders names to access resources  User need to connect to each server

32 Dfs: Scenario 2 Server4 \Policy Server 2 \Data Server 1 \Install Server 3 \Sales Using Dfs  Have a server with Dfs and Dfs links created  User need to connect to a single server  User doesn’t need to know servers and folders names Dfs server Link to Install Link to Policy Link to Data Link to Sales

33 Dfs implementation in Win 2000 Standalone Dfs  Created on standalone servers (Workgroup)  Doesn’t take advantage of the Active Directory  Offer a single level of Dfs links There are two Dfs models: Domain-Based Dfs  Created on a Domain controller or Member server (in a Domain)  Uses Active Directory  Offer a deep hierarchy Dfs links

34 Dfs implementation in Win 2000 Only 1 Dfs root per server is allowed Dfs can be created on FAT or NTFS partitions To create a standalone Dfs root, use the Distributed File System snap-in

35 Disk Quotas Disk Quotas needed because  Many users save data on shared folders  Users must be prevented from filling disk capacity Disk Quotas options  Enable Disk quotas w/o limiting disk usage  Set a default quota for all users  Determine quotas on per-user basis Disk quotas are determined based on the uncompressed files/folders sizes

36 Taking ownership 1) Disk quotas are based on files/folders ownership 2) If you have the Take ownership permission on a file/folder, you can take its ownership.