is451quizreview

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is451quizreview
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2014-04-09 04:05:10
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is451quiz2 quiz review
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  1. Concept of network mgmt
    • • Any complex system with many interacting components must be monitored, managed and controlled
    • • In the early 1980 networks expansion prompted the need for automated network management
    • • In general, network management is a service that employs a variety of tools, applications, and devices to assist human network managers in monitoring and maintaining networks.
  2. why is network mgmt necessary?
    • Network management scenarios
    • • Detecting failure of an interface card in a device
    • • Host monitoring
    • • Traffic monitoring to optimize resource deployment
    • • Detecting rapid changes in routing tables
    • • Intrusion detection
  3. ISO FCAPS network mgmt model and its 5 conceptual areas
    • • Fault management – log, detect and respond to fault conditions in the network
    • • Configuration management – track devices and their h/w and s/w configs
    • • Accounting management - specify, log and control user access to network resources
    • • Performance management – quantify, measure, report, analyze and control performance of network components
    • • Security Management – control access to network resources according to some well-defined policy
  4. network mgmt architecture
    • Most network management architectures use the same basic structure and set of relationships. End stations (managed devices), such as computer systems and other network devices, run software that enables them to send alerts when they recognize problems (for example, when one or more user-determined thresholds are exceeded). Upon receiving these alerts, management entities are programmed to react by executing one, several, or a group of actions, including operator notification, event logging, system shutdown, and automatic attempts at system repair.
    • Management entities also can poll end stations to check the values of certain variables. Polling can be automatic or user-initiated, but agents in the managed devices respond to all polls. Agents are software modules that first compile information about the managed devices in which they reside, then store this information in a management database, and finally provide it (proactively or reactively) to management entities within network management systems (NMSs) via a network management protocol. Well-known network management protocols include the Simple Network Management Protocol (SNMP) and Common Management Information Protocol (CMIP). Management proxies are entities that provide management information on behalf of other entities.
  5. different version of SNMP
    • Since the inception SNMP, has gone through significant upgrades. However SNMP v1 and v2c are the most implemented versions of SNMP. Support to SNMP v3 has recently started catching up as it is more secured when compare to its older versions, but still it has not reached considerable market share.
    • SNMPv1:
    • This is the first version of the protocol, which is defined in RFCs 1155 and 1157
    • SNMPv2c:
    • This is the revised protocol, which includes enhancements of SNMPv1 in the areas of protocol packet types, transport mappings, MIB structure elements but using the existing SNMPv1 administration structure ("community based" and hence SNMPv2c). It is defined in RFC 1901, RFC 1905, RFC 1906, RFC 2578.
    • SNMPv3:
    • SNMPv3 defines the secure version of the SNMP. SNMPv3 also facilitates remote configuration of the SNMP entities. It is defined by RFC 1905, RFC 1906, RFC 3411, RFC 3412, RFC 3414, RFC 3415.
    • Though each version had matured towards rich functionalities, additional emphasis was given to the security aspect on each upgrade. Here is a small clip on each editions security aspect.
    • SNMP v1 Community–based security
    • SNMP v2c Community–based security
    • SNMP v2u User–based security
    • SNMP v2 Party–based security
    • SNMP v3 User–based security
  6. SMI- how are managed objects defined; how information is stored in MIB
    • • MIB (Management Information Base) – virtual information store for a collection of managed objects
    • • Describes structure of management data on managed device
    • • Each variable that describes some part of device configuration is identified by a unique OID (object ID)
    • • Vendors define MIB variables for their own use
    • • MIB II – standard MIB implemented by all managed objects
  7. what is ASN.1?
    a standard for describing data that is independent of machine-specific encoding.
  8. Why is ASN.1 necessary to defined managed objects?
    • SMI (Structure of management information)
    • • SMI is the language used to define the management information residing in a managed object – logically
    • • SMI states that each managed object should have a name, syntax and encoding
    • • SMI is a subset of ASN.1 - a standard for describing data that is independent of machine-specific encoding.
  9. How are managed objects named? (OID) Hierarchical nature of object orgs.

  10. What transport does SNMP use and why?
    UDP Transport - lower overhead, cut down overhead, quick delivery
  11. Understand SNMP operations
    • • Get - is a request sent by the manager to the managed device. It is performed to retrieve one or more values from the managed device.
    • • Getnext - retreive a group of values; This operation is similar to the GET. The significant difference is that the GET NEXT operation retrieves the value of the next OID in the MIB tree.
    • • getbulk (SNMPv2 and SNMPv3) - retreive a section of a table; used to retrieve voluminous data from large MIB table.
    • • Set - change value or create a new row in the table; used by the managers to modify or assign the value of the Managed device.
    • • Getresponse -
    • • Trap - asynchronous operation; Unlike the above commands which are initiated from the SNMP Manager, TRAPS are initiated by the Agents. It is a signal to the SNMP Manager by the Agent on the occurrence of an event.
    • • notification (SNMPv2 and SNMPv3)
    • • inform (SNMPv2 and SNMPv3) - This command is similar to the TRAP initiated by the Agent, additionally INFORM includes confirmation from the SNMP manager on receiving the message.
    • • report (SNMPv2 and SNMPv3) - allow SNMP engines to communicate with each other (mainly to report problems with processing SNMP messages).
  12. what is a directory?
    • A directory service is the collection of software, hardware,
    • processes, policies, and administrative procedures involved in making the information in your directory available to the users of your directory.
    • It’s a hierarchical database that stores information in an object-oriented, rather than a tabular form, as an RDBMS does. The difference in the architecture is in the type of services that a directory provides.
    • Your directory service includes at least the following components:
    • • Information contained in the directory
    • • S/W servers holding this information
    • • S/W clients acting on behalf of users or other entities
    • accessing this information
    • • H/W on which these clients and servers run
    • • Policies governing access
    • • S/W and procedures for maintainance and monitoring
  13. Directory as a database comparison
    • Directory is a specialized database
    • • Directories typically have a higher read-to-write ratio than databases.
    • • Directories are typically more easily extended
    • • Directories are usually more widely distributed
    • • Directories are often replicated on a higher scale
    • • Directories usually have very different performance characteristics
    • • Support for standards is important in directories, less so in databases.
  14. X.500 directory architecture
    • The X.500 Directory is developed for storing information about objects, such as organizations, persons, distribution lists, groups, certification authorities, etc. The information stored about an object is identity information and other information associated with the object, e.g. its postal address.
    • • Implemented as a distributed database
    • • All network entities are implemented as objects with attributes
    • • Schema defines the directory “blueprint”
  15. Client-server (DUA, DSA)
    • DUA - Directory User Agent
    • DSA - Directory Server Agent
  16. Protocols: DAP, DSP
    • DAP - Directory Access Protocol
    • DSP - Directory Server Protocol
  17. Directory naming conventions: DN, RDN
    • DN (distinguished name)- Each object is identified by it’s distinguished name (DN) that’s unique in the directory (e.g. cn=ChocCookie ,ou=recipes, dc=foobar, dc=com; Printer1.is.umbc.edu; dglazer.umbc.edu)
    • RDN - Each object has RDN – simple object name that is unique within a tree level (e.g. Printer1, dglazer)
  18. what is LDAP?
    • "Lightweight Directory Access Protocol"
    • It was originally designed to provide access to X.500 databases; however it is now more common to find LDAP servers in a standalone capacity. LDAP has become the defacto standard for internet directory services
    • LDAP operations are divided into 3 areas: Authentication, Interrogation, Update
  19. How does LDAP relate to X.500?
    • • LDAP was originally developed as an alternative to X.500 DAP protocol
    • • It was designed to use TCP/IP instead of OSI protocol stack (“lighter protocol”).
    • • LDAP evolved into a complete directory service
    • • LDAP’s architecture and naming structure are based on X.500 standard
    • • Although today’s version of DAP also runs over TCP/IP, LDAP remains the popular option for connection to a Directory.
  20. LDAP protocol operations
    • • Authentication: Open, bind and unbind; allows the client to prove its identity to the DSA.
    • • Interrogation: Search, compare; provides a method for the client to interrogate the directory information tree.
    • • Update: Add, Modify, Delete; defines a mechanism for the client to add or modify information in the directory information tree.
  21. common directory products
    (Microsoft Active Directory ;Novell eDirectory; Apple Open Directory ; Sun Java System Directory Server;Apache Directory Server ; Oracle Internet Directory)
  22. Primary Goals of SNMPv3
    • • Check message integrity - To verify that each received message has not been modified during its transmission .
    • • User authentication - To verify the identity of the user on whose behalf a received message claims to have been generated.
    • • Message timestamp – to detect outdated messages
    • • Message confidentiality - To assure that the contents of each received message are protected/encrypted.
  23. SNMPv3 User-based Security Model
    • • USM communication mechanisms available:
    • • Communication without authentication and privacy (NoAuthNoPriv).
    • • Communication with authentication and without privacy (AuthNoPriv).
    • • Communication with authentication and privacy (AuthPriv).
    • • Different authentication and privacy protocols supported - Currently, the MD5 and SHA authentication protocols and the CBC_DES and CFB_AES_128 privacy protocols are supported in the USM.
  24. SNMPv3 VCAM
    • • The Access Control Subsystem of an SNMP entity has the responsibility for checking whether a specific type of access to a specific managed object is allowed.
    • • Access control occurs in the agent when processing SNMP retrieval or modification request messages from a manager, and also when a notification message must be sent to the manager.
    • • Elaborates on the concept of community strings in the previous versions of SNMP
  25. SNMPv3 security framework/ two core modules within the framework
    • • Two core modules within the framework are the User-based Security Model (USM) and the View-based Access Control Model (VACM).
    • • The USM is in charge of authenticating/encrypting/decrypting SNMP packets
    • • The VACM is in charge of administering access to MIB data.
  26. Simple Network Management Protocol
    • • Protocol for network management, part of TCP/IP suite
    • • Current version SNMPv3
    • • Includes communication protocol, set of data definitions and database schema
  27. SNMP basic components
    • • Basic components:
    • Managers/NMS
    • Managed devices
    • SNMP Agents
    • MIB
  28. A directory "blueprint" that describes structure of information in the directory is …
    A. Schema
    B. Attribute
    C. DN (Distinguished Name)
    D. Object
    A. Schema
    (this multiple choice question has been scrambled)
  29. Which of the following SNMP commands is not originated by NMS?
    A. Get
    B. Get-next
    C. Set
    D. Trap
    D. Trap
    (this multiple choice question has been scrambled)
  30. What is the name of a virtual database of managed objects that SNMP agent tracks?
    A. SNMP
    B. OID
    C. SMI
    D. MIB
    D. MIB
    (this multiple choice question has been scrambled)
  31. An SNMP __ is responsible for responding to polls from and sending traps to an SNMP ___.
    A. NMS; Manager
    B. Manager; agent
    C. NMS; protocol
    D. Agent; MIB
    E. Agent; manager
    E. Agent; manager
    (this multiple choice question has been scrambled)
  32. A directory client is …
    A. DSA
    B. DSP
    C. DAP
    D. DUA
    D. DUA
    (this multiple choice question has been scrambled)
  33. Why is it preferable to use UDP transport for SNMP?
    A. It is more reliable
    B. It uses encryption
    C. It is more secure
    D. It has lower overhead
    D. It has lower overhead
    (this multiple choice question has been scrambled)
  34. What components of Directory Services holds the data repository?
    A. DSA
    B. LDAP
    C. DAP
    D. DUA
    A. DSA
    (this multiple choice question has been scrambled)
  35. Each piece of information that describes some aspect of a directory entry is called …
    A. DUA
    B. An attribute
    C. An object
    D. A schema
    B. An attribute
    (this multiple choice question has been scrambled)
  36. What SNMP command would bee used to make changes in a router configuration?
    A. Get-next
    B. Get
    C. Set
    D. Trap
    C. Set
    (this multiple choice question has been scrambled)
  37. What type of access is the most common in the Directory Services?
    A. Read
    B. Update
    C. Delete
    D. Write
    A. Read
    (this multiple choice question has been scrambled)
  38. What does OID identifies about a MIB object?
    A. It's position in the MIB subtree
    B. The number of its subnodes
    C. It's value
    D. It's priority
    A. It's position in the MIB subtree
    (this multiple choice question has been scrambled)
  39. Which of the following is true about Directory Services replication?
    a. It allows directory database to be distributed
    b. It supports directory access load-balancing
    c. It supports directory fault-tolerance
    d. All of the above
    d. All of the above
  40. Which of the following protocols is used for directory access?
    A. DISP
    B. DAP
    C. DSP
    D. MIB
    B. DAP
    (this multiple choice question has been scrambled)
  41. What standard MIB is required to be implemented by all devices?
    A. MIB Root
    B. MIB II
    C. MIB-Main
    D. MIB I
    B. MIB II
    (this multiple choice question has been scrambled)
  42. What is used to define management information in MIBs?
    A. SNMP
    B. LDAP
    C. OID
    D. SMI
    D. SMI
    (this multiple choice question has been scrambled)
  43. Which of the following acts as a primary key for a directory?
    A. Object
    B. RDN
    C. DN
    D. Schema
    C. DN
    (this multiple choice question has been scrambled)
  44. Which of the following is a difference between LDAP-based and X.500-based directories?
    A. Transport/network protocol stack used/for directory access
    B. Client-server architecture
    C. Directory structure
    D. Naming convention
    A. Transport/network protocol stack used/for directory access
    (this multiple choice question has been scrambled)
  45. Directory Information Tree represents …
    A. Hierarchical directory structure and object organization
    B. Client-server directory model
    C. Directory schema
    D. Set of directory object permissions
    A. Hierarchical directory structure and object organization
    (this multiple choice question has been scrambled)
  46. How are RDN and DN related?
    A. RDN is part of DN
    B. They are not related
    C. DN is part of RDN
    D. They represent the same thing
    A. RDN is part of DN
    (this multiple choice question has been scrambled)
  47. Which of the following does SNMPv3 support?
    a. Message integrity
    b. Data encryption
    c. Authentication
    d. All of the above
    d. All of the above
  48. What are the goals of security management?
    A. Control access to network components according to a well-defined policy
    B. Specify, log and regulate user access to network resources
    C. Measure, analyze and control performance of network components
    D. Track and control inventory of network components
    A. Control access to network components according to a well-defined policy
    (this multiple choice question has been scrambled)
  49. What are the goals of configuration management?
    A. Track and control inventory of network components
    B. Control access to network components according to a well-defined policy
    C. Log and regulate user access to network resources
    D. Measure, analyze and control performance of network components
    A. Track and control inventory of network components
    (this multiple choice question has been scrambled)
  50. What SNMP command is asynchronous?
    A. Set
    B. Get-bulk
    C. Trap
    D. Get-next
    C. Trap
    (this multiple choice question has been scrambled)
  51. What component of Directory Services maintains and communicates directory information?
    A. LDAP
    B. DSA
    C. DAP
    D. DUA
    B. DSA
    (this multiple choice question has been scrambled)
  52. In network management applications, the ___ is software packaged with a network element that collects information about that element.
    A. Agent
    B. Manager
    C. NMS
    D. MIB
    A. Agent
    (this multiple choice question has been scrambled)
  53. Which of the following represents the format of a MIB OID?
    A. 1 3 6 3 2
    B. 1.3.6.3.2
    C. 1-3-6-3-2
    D. 1#3#6#3#2
    B.1.3.6.3.2
    (this multiple choice question has been scrambled)
  54. What is the purpose of directory replication process?
    • It allows directory database to be distributed
    • It supports directory access load-balancing
    • It supports directory fault-tolerance
  55. How are multimedia applications different from elastic applications such as email, web, etc?
    • Multimedia vs. (conventional) Data Applications
    • ○ analog “continuous” media: encoding, decoding & playback
    • ○ service requirements
  56. What are some of the service transport protocol requirements?
    • TCP/UDP/IP: “best-effort service”
    • no guarantees on delay, loss
    • Today’s Internet multimedia applications use application-level techniques to mitigate (as best possible) effects of delay, loss
  57. How are audio digitized and compressed for streaming?
    • Audio
    • ○ analog audio signal sampled at constant rate
    • ○ each sample quantized, each quantized value represented by bits, e.g., 8 bits for 256 values
    • ○ receiver converts bits back to analog signal
  58. How are video digitized and compressed for streaming?
    • Digital Video
    • Sampling the analog signal
    • ○ Sample at some fixed rate (e.g., 24 or 30 times per sec)
    • ○ Each sample is an image
    • Quantizing each sample
    • ○ Representing an image as an array of picture elements
    • ○ Each pixel is a mixture of colors (red, green, and blue)
  59. streaming, stored audio, video: types of multimedia applications:
    • Clients request audio/video files from servers and pipeline reception over the network and display
    • Interactive: user can control operation (similar to VCR: pause, resume, fast forward, rewind, etc.)
    • Delay: from client request until display start can be 1 to 10 seconds
  60. conversational voice/video over IP/ Interactive Real-Time: types of multimedia applications:
    • Phone conversation or video conference
    • E.g., skype, VoIP
    • More stringent delay requirement than Streaming and Unidirectional because of real-time nature
  61. streaming live audio, video/ Unidirectional Real-Time: types of multimedia applications:
    • E.g., real-time video broadcasting of a sport event
    • similar to existing TV and radio stations, but delivery on the network
    • Non-interactive, just listen/view
  62. What are the challenges of streaming multimedia?
    • TCP/UDP/IP suite provides best-effort, no guarantees on expectation or variance of packet delay
    • Streaming applications delay of 5 to 10 seconds is typical and has been acceptable, but performance deteriorate if links are congested (transoceanic)
    • Real-Time Interactive requirements on delay and its jitter have been satisfied by over-provisioning (providing plenty of bandwidth), what will happen when the load increases?...
  63. How do network delay and jitter affect multimedia applications? How does client-side buffering work and help with network jitter?
    • ○ but network delays are variable (jitter), so will need client-side buffer to match playout requirements
    • ○ Client-side buffering, playout delay compensate for network-added delay, delay jitter
    • ○ Jitter is the variability of packet delays within the same packet stream
  64. Streaming multimedia: UDP
    • server sends at rate appropriate for client
    • ○ often: send rate = encoding rate = constant rate
    • ○ transmission rate can be oblivious to congestion levels
    • short playout delay (2-5 seconds) to remove network jitter
    • error recovery: application-level, time permitting
    • UDP may not go through firewalls
    • RTP (or similar) is used to encapsulate video over UDP
    • RTSP is used for control connection for session changes (play, pause)
  65. Streaming multimedia: HTTP
    • send at maximum possible rate under TCP
    • fill rate fluctuates due to TCP congestion control, retransmissions (in-order delivery)
    • larger playout delay: smooth TCP delivery rate
    • HTTP/TCP passes more easily through firewalls
  66. RAID 0 configuration…
    A. Stripes data and parity across multiple drives
    B. Mirrors data across 2 drives
    C. Stripes data across multiple drives with an additional drive dedicated to parity
    D. Stripes data and provides no parity
    D. Stripes data and provides no parity
    (this multiple choice question has been scrambled)
  67. What is the difference between disk mirroring and disk duplexing?
    A. More disk controllers are used in mirroring
    B. More disks are used in duplexing
    C. More disk controllers are used in duplexing
    D. More disks are used in mirroring
    C. More disk controllers are used in duplexing
    (this multiple choice question has been scrambled)
  68. What presents a block level interface to the network?
    A. SAN
    B. RAID
    C. DAS
    D. NAS
    A. SAN
    (this multiple choice question has been scrambled)
  69. Software RAID processing is handled by:
    A. Computer operating system
    B. Disc drives
    C. Disk controller
    D. SCSI
    A. Computer operating system
    (this multiple choice question has been scrambled)
  70. What aspect of RAID 0 makes it different from all other RAID levels?
    A. It offers read/write performance improvement
    B. It has no redundancy
    C. It uses more than 1 disk
    D. It uses disk striping
    B. It has no redundancy
    (this multiple choice question has been scrambled)
  71. RAID 1 with 2 disk controllers is also called…
    A. Duplexing
    B. Switching
    C. Mirroring
    D. Striping
    A. Duplexing
    (this multiple choice question has been scrambled)
  72. iSCI is encapsulated in …
    A. RAID
    B. TCP/IP
    C. SCSI
    D. Fibre Channel
    B. TCP/IP
    (this multiple choice question has been scrambled)
  73. Storage attached locally to a server through block-level interface is called:
    A. NAS
    B. DAS
    C. SAN
    D. iSCI
    B. DAS
    (this multiple choice question has been scrambled)
  74. Define Network (Distributed) file systems and give an example of when one needs to be used.
    • Client/server based application that allows clients to access and process data stored on the server as if it were on their own computer
    • (SMB, CIFS, NFS, AFS)
  75. Compare and contrast traditional Fibre Channel SANs and IP-based SANs, including their respective protocols. What components are the same and what are different>
    • Fibre Channel SANs use Fibre Channel protcol, it’s expensive, its use dedicated system/ architecture
    • IP-based SANs use iSCSI protocol, use existing infrastructure, use existing hardware and software
    • They both transmit SCSI commands over SANs
  76. Draw Directory Services application architecture, include discussion/ representation of centralized/ distributed nature of a directory database.
    • DRAWING: SEE NOTES
    • DUA->DAP->DSA->DSP->DSA
  77. Label the 2 pictures below with their corresponding network storage solution methods and described the type of access (file-level or block-level) on each corresponding network
    1. Application -> Network -> File System -> Disk Storage :
    2. Application -> File System -> Network-> Disk Storage :
    • 1. Application -> Network -> File System -> Disk Storage : NAS; Access type: File-level
    • 2. Application -> File System -> Network-> Disk Storage : SAN; Access type: Block-level access

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