1. Network+ Guide to Networks 5th Edition
Chapter 9
Network Operating Systems

2. Objectives
Describe characteristics common to all NOSs (network operating systems)
Compare and evaluate NOSs to select the right one for your Network
Define the requirements for and features of the Windows Server 2008 NOS
Define the requirements for and features of UNIX and Linux NOSs
Create users and groups and assign file permissions on systems running Windows Server 2008 and UNIX
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3. Characteristics of Network Operating Systems
Based on client/server architecture
NOS manages resource sharing
NOS provides many other functions
Some built in
Some configured at installation
Default, customizable settings
NOS components vary by NOS version and type
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4. Network Operating Systems and Servers
Networks use servers exceeding minimum hardware
Determining optimal server hardware
Questions
What kinds of applications will run on the server?
How many clients will connect to the server?
How much storage space will each user need?
How much downtime, if any, is acceptable?
What can the organization afford?
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5. Network Operating Systems and Servers (cont’d.)
Determining optimal server hardware (cont’d.)
Applications influence:
Type of application
Resources used
Processing burden
Vendor reputation requirements
High quality, dependability, excellent technical support
Reliable server
Spend as much as necessary
Component failure: widespread effects
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6. Client Support Important NOS function NOS client support tasks
Allows efficient communication, resource sharing
NOS client support tasks
Creating and managing client accounts
Enabling clients to connect to the network
Allowing clients to share resources
Managing clients’ access to shared resources
Facilitating communication between clients
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7. Client/Server Communication
Logon process
Redirector
Intercepts requests, determines where to handle
File access protocol
Windows XP client communication with Windows Server 2008
CIFS (Common Internet File System)
Older protocol SMB (Server Message Block)
Broad support allows every client type to authenticate, access resources
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8. Client/Server Communication (cont’d.)
Figure 9-1 A client connecting to an NOS
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9. Client/Server Communication (cont’d.)
Middleware
Translates requests, responses between client, server
3-tier architecture
Client/server environment incorporating middleware
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10. Client/Server Communication (cont’d.)
Figure 9-2 Middleware between clients and a server
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11. Users and Groups After NOS client authentication Administrator account
Client gains access to NOS services, resources
Administrator account
Most privileged user account
Unlimited rights to server, domain resources, objects
Created by default
Root on UNIX or Linux systems
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12. Users and Groups (cont’d.)
User names
NOS grants each network user access to files and other shared resources
Groups
Basis for resource and account management
Assists in resource sharing and security control
Example: network administrator for public elementary school
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13. Users and Groups (cont’d.)
Table 9-1 Providing security through groups
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14. Users and Groups (cont’d.)
Nesting or hierarchical group arrangement
Simplifies management
Group arrangement
Affects permissions granted to each group’s members
Inherited permissions
Passed down from parent group to child group
After user, group restrictions applied
Client allowed to share network resources
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15. Identifying and Organizing Network Elements
Modern NOSs
Similar patterns for organizing information
Users, printers, servers, data files, and applications
Directory
List organizing resources
Associates resources with characteristics
Example: file system directory
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16. LDAP (Lightweight Directory Access Protocol)
Used to access information stored in directory
Object
Thing or person associated with network
Attributes
Properties associated with object
Schema
Set of definitions
Kinds of objects and object-related information contained in directory
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17. LDAP (cont’d.) Schema (cont’d.): Two types of definitions:
Classes (object classes): identifies object type specified in directory
Attributes: stores information about object
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18. Figure 9-3 Schema elements associated with a User account object
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19. LDAP (cont’d.) Containers (OUs or organizational units) LDAP standard
Logically defined receptacles
Assemble similar objects
Account
User record containing all properties
LDAP standard
Directories and contents form trees
Tree
Logical representation of multiple, hierarchical levels within directory
Root, branches, leafs
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20. Identifying and Organizing Network Elements (cont’d.)
Figure 9-4 A directory tree
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21. LDAP (cont’d.) Before installing NOS Book example Plan directory tree
Consider current, future needs
Book example
New manufacturing firm: Circuits Now
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22. Identifying and Organizing Network Elements (cont’d.)
Figure 9-5 Two possible directory trees for the same organization
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23. Sharing Applications Shared applications Application licensing types
Often installed on file server
Specifically designed to run applications
Application licensing types
Per user licensing
Per seat licensing
Site license
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24. Sharing Applications (cont’d.)
Installing application on server
Purchase appropriate type and number of licenses
Verify server resources
Install application
Make application available
Provide users access to application
NOS responsible for arbitrating file access
Problem with shared file access
Multiple users simultaneously accessing same data files, same program files
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25. Sharing Printers
Increases resource management efficiency; reduces costs
Print server
Manages print services
Printer attaches to print server
Directly
To convenient network location
All NOSs perform common tasks in managing printers
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26. Sharing Printers (cont’d.)
Figure 9-6 Shared printers on a network
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27. Sharing Printers (cont’d.)
To create new printer
Install printer driver
Provides printer availability to users
Ensure appropriate printer queue user rights
Networked printers
Appear as icons in Printers folder
Client redirector
Determines where print request should transmitted
Network, workstation
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28. Managing System Resources
Limited server system resources
Required by multiple users
Modern NOSs capabilities
Maximize server memory, processor, bus, and hard drive use
Accommodates more client requests faster
Improves overall network performance
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29. Memory Virtual memory can boost total memory available
Physical memory: RAM chips
Physical memory required by server varies
Task dependent
Virtual memory: stored on hard drive
Page file (paging file, swap file)
Managed by operating system
Paging
Moving blocks (pages) from RAM into virtual memory
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30. Memory (cont’d.) Virtual memory advantages Virtual memory disadvantage
Easily expands memory available to server applications
Engaged by default
Virtual memory disadvantage
Slows operations
Hard drive access versus physical memory access
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31. Multitasking (cont’d.)
Execution of multiple tasks at one time
All operating system perform
Does not mean performing more than one operation simultaneously
Preemptive multitasking (time sharing: UNIX)
Happens quickly
Appearance of tasks occurring simultaneously
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32. Multiprocessing (cont’d.)
Routine of sequential instructions that runs until goal is achieved
Thread
Self-contained; well-defined task within process
Main thread
All processes have one
One processor systems
One thread handled at any time
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33. Multiprocessing (cont’d.)
Support use of multiple processors to handle multiple threads
Technique to improve response time
Splits tasks among more than one processor
Expedites single instruction completion
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34. Multiprocessing (cont’d.)
Symmetric multiprocessing
Splits all operations equally among two or more processors
Asymmetric multiprocessing
Assigns each subtask to specific processor
Multiprocessing advantage to servers with high processor usage
Numerous tasks simultaneously
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35. Windows Server 2008 Released February 2008
Enhancement of Windows Server 2003
GUI (graphical user interface)
Pictorial representation of computer function
NOS GIUs
Enable administrator to manage files, users, groups, security, and printers
Enhanced security, reliability, remote client support, and performance
New server management features
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36. Windows Server 2008 (cont’d.)
Editions
Standard Edition
Web Edition
Enterprise Edition
Datacenter Edition
Popular NOS
Address most network administrator’s needs well
Well-established vendor
Device; program compatibility
Larger market offers technical support
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37. Windows Server 2008 (cont’d.)
General benefits
Offers several general benefits
Offers simple user interfaces
Disadvantage
Past criticism for performance, security
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38. Hardware Requirements
Server components
Processing power, memory, and hard drive space
Windows Server Catalog
Windows Server 2008 compatible computer components
Available online
Consult it prior to hardware purchases
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39. Hardware Requirements (cont’d.)
Table 9-2 Minimum hardware requirements for Windows Server 2008, Standard Edition
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40. Memory Model Addressing schemes Assigns each application (process)
32-bit addressing scheme
64-bit addressing scheme
Assigns each application (process)
Own 32-bit memory area
Logical subdivision memory available to server
Important Windows Server 2008 feature
Install more server physical memory
Uses virtual memory
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41. Figure 9-7 The Windows Server 2008 Performance Options Advanced tab
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42. NTFS (New Technology File System)
Methods of organizing, managing, and accessing files
Through logical structures, software routines
NTFS (New Technology File System)
Installed by default
Disk data distribution
Disks divided into allocation units (clusters)
Allocation units combine to form partition
Logically separate hard disk storage area
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43. NTFS (cont’d.) Advantages Drawback
Secure, reliable, and file compression
Handles massive files
Allow fast access to resources
Used on all Windows operating system versions
Since Windows NT
Offers many features
Drawback
Cannot be read by older operating systems
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44. Active Directory Directory service
Originally designed for Windows 2000 Server
Enhanced with Windows Server 2008
Windows Server 2008 network
Workgroup model
Domain model
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45. Workgroups Peer-to-peer network Decentralized management
Each computer has own database
User accounts, security privileges
Significantly more administration effort
Practical for small networks
Few users
Simple to design, implement
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46. Domains Group of users, servers, and other resources
Share centralized account and security information database
Client/server network
Active directory
Contains domain databases
Easier to organize and manage resources and security
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47. Domains (cont’d.) Figure 9-8 Multiple domains in one organization
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48. Domains (cont’d.) Domain not confined by geographical boundaries
Domain controllers
Contains directory containing information about objects in domain
Member servers
Do not store directory information
Replication
Process of copying directory data to multiple domain controllers
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49. Domains (cont’d.)
Figure 9-9 Domain model on a Windows Server 2008 network
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50. OUs (Organizational Units)
Hold multiple objects having similar characteristics
Can be nested
Provides allows simpler, more flexible administration
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51. Trees and Forests Directory structure above domains Domain tree
Large organizations use multiple domains
Domain tree
Organizes multiple domains hierarchically
Root domain
Active Directory tree base
Child domains
Branch off from root domain
Separate groups of objects with same policies
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52. Trees and Forests (cont’d.)
A collection of one or more domain trees
Share common schema
Domains within a forest can communicate
Domains within same tree
Share common Active Directory database
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53. Trees and Forests (cont’d.)
Figure 9-10 A tree with multiple domains and OUs
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54. Trust Relationships Relationship between two domains
One domain allows another domain to authenticate its users
Active Directory supports two trust relationship types
Two-way transitive trusts
Explicit one-way trusts
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55. Trust Relationships (cont’d.)
Figure 9-11 Two-way trusts between domains in a tree
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56. Trust Relationships (cont’d.)
Figure 9-12 Explicit one-way trust between domains in different trees
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57. Naming Conventions Active Directory naming (addressing) conventions
Based on LDAP naming
Internet namespace
Complete hierarchical names database
Used to map IP addresses to hosts’ names
Active Directory namespace
Collection of object names, associated places in Windows Server 2003, Server 2008 network
Two namespaces are compatible
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58. Naming Conventions (cont’d.)
Windows Server 2008 network object
Three different names
DN (distinguished name): DC (domain component) and CN (common name)
RDN (relative distinguished name)
UPN (user principal name)
GUID (globally unique identifier)
128-bit number
Ensures no two objects have duplicate names
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59. Naming Conventions (cont’d.)
Figure 9-13 Distinguished name and relative distinguished name
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60. Server Management Setting up and managing server Choose role
Reflects server’s primary purpose
Conduct server management task
Server Manager: GUI tool
Many functions available
Use Server Manager window
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61. Server Management (cont’d.)
Figure 9-14 Windows Server 2008 Server Manager
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62. Server Management (cont’d.)
Figure 9-15 Server Manager’s Reliability and Performance window
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63. UNIX and Linux Popular NOSs Some difficulty to master UNIX
Provide resource sharing
Older
UNIX develop in 1969
UNIX preceded, led to TCP/IP protocol suite development
Most Internet servers run UNIX
Efficient and flexible
Some difficulty to master UNIX
Not controlled, distributed by single manufacturer
Some version nonproprietary and freely distributed
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64. A Brief History of UNIX Late 1960s: UNIX operating system 1970s 1980s
Antitrust laws and AT&T
Anyone could purchase the source code
New versions of UNIX appeared
System V, BSD
1980s
Rights changes hands, now owned by Novell
Open Group owns UNIX trademark
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65. Varieties of UNIX Many varieties (flavors, distributions)
Share several features
UNIX operating system
Divided into two main categories
Proprietary
Open source
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66. Proprietary UNIX Source code unavailable
Available only by purchasing licensed copy from Novell
Vendors
Apple Computer: Mac OS X Server
Sun Microsystems: Solaris
IBM: AIX
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67. Proprietary UNIX (cont’d.)
Proprietary UNIX system advantages
Accountability and support
Optimization of hardware and software
Predictability and compatibility
Proprietary UNIX system drawback
No source code access
No customization
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68. Open Source UNIX Customizable Not owned by any one company
No licensing fees
Open source software (freely distributable software)
UNIX GNU, BSD, and Linux
Variety of implementations
Run on wider range of systems
Key difference from proprietary implementations
Software license
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69. Two Flavors of UNIX Solaris Linux follows standard UNIX conventions
Sun Microsystems
Runs on SPARC-based servers
All commercially supported operating system benefits
Use: Runs intensive applications
Examples: large, multiterabyte databases, weather prediction systems, and large economic modeling applications
Linux follows standard UNIX conventions
Highly stable, free
Developed by Linus Torvalds (1991)
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70. Two Flavors of UNIX (cont’d.)
All UNIX and Linux versions
Offer host of features
TCP/IP protocol suite
Applications to support networking infrastructure
Support non-IP protocols
Programs necessary for routing, firewall protection, DNS services, DHCP services
Operates over many different network topologies, physical media
Efficiently and securely handle growth, change, stability
Source code used, thoroughly debugged
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71. Hardware Requirements
Similar to Windows Server 2003, Server 2008
Key differences
UNIX, Linux operating system can act as workstation or server operating system
GUI (graphical user interface) remains optional
No single “right” server configuration exists
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72. Solaris Hardware Requirements
Table 9-3 Minimum hardware recommendations for Solaris 10
Computers containing Sun SPARC processors or Intel-based processors
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73. Linux Hardware Requirements
Table 9-4 Minimum hardware recommendations for a Linux server
Linux servers adhere to certain minimum requirements
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74. UNIX Multiprocessing UNIX and Linux Support processes and threads
Allocate separate resources (memory space) to each process
When created
Manage access to resources
Advantage: prevents one program from disrupting system
Support symmetric multiprocessing
Different versions support different number of processors
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75. The UNIX Memory Model Use physical, virtual memory efficiently
Allocate memory area for each application
Share memory between programs when possible
Use 32-bit addressing scheme
Programs access 4 GB memory
Most systems also run on CPUs employing 64-bit addresses
18 exabytes (264 bytes) memory
Virtual memory
Disk partition or file
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76. The UNIX Kernel Kernel Kernel module
Core of all UNIX and Linux systems
Kernel module
File containing instructions for performing specific task
Reading data from and writing data to hard drive
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77. UNIX System File and Directory Structure
Hierarchical file system
Disk directories may contain files, other directories
/boot directory: kernel, system initialization files
/sbin directory: applications, services
/var directory: variable data
/home directory: created for new users
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78. UNIX System File and Directory Structure (cont’d.)
Figure 9-16 UNIX file system hierarchy
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79. UNIX File Systems Two broad categories Disk file systems
Network file systems
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80. Disk File Systems Organizing, managing, accessing files
Through logical structures, software routines
Linux native file system type
ext3: “third extended” file system
Solaris native file system
UFS (UNIX file system)
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81. Network File Systems Analogous to Windows shares
Attach shared file systems (drives)
From Windows, other UNIX servers
Share files with users on other computers
UNIX and Linux popular remote file system type
Sun Microsystems’ NFS (Network File System)
Open source application implementing Windows SMB, CIFS file system protocols
Samba
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82. A UNIX and Linux Command Sampler
Many system administrators prefer command line
GUI executes commands
Responds to mouse clicks
Command interpreter (shell)
Accepts keyboard commands and runs them
Man pages (manual pages)
Full documentation of UNIX commands
Nine sections
apropos command
Helps find possible man page entries
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83. A UNIX and Linux Command Sampler (cont’d.)
Commands function like sentences
Rules guide UNIX command use
Significant UNIX and Windows command-line interface difference
Character separating directories
Windows separator character: ( \ )
UNIX separator character: ( / )
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84. Table 9-5 Commonly used UNIX commands
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85. A UNIX and Linux Command Sampler (cont’d.)
Most frequently used UNIX command ls
Provides file information
Stores in file inode (information node)
ls –l command
Access permissions field
Files type designations
Pipe
Direct one command output to input of another command
Unix: vertical bar ( | )
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86. Figure 9-17 Example of output from ls -l
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87. Figure 9-18 Anatomy of ls –l output
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88. Summary Characteristics common to all NOS
Systems and servers, client support, identifying and organizing network elements, sharing applications and printers, managing system resources
Windows Server 2008 network structure
Unix and Linux concepts and features
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