Basic CS-Networks [TCS Placement]: Sample Questions 67 - 68 of 133

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Question 67

Networks
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Describe in Detail

Essay▾

What are the improvements made in CAS in . NET 4.0?

Explanation

  • CAS mechanism controls and configures the ability of managed code.
  • Earlier policy was applicable for only native applications and hence security guarantee was limited.
  • Developers thus used alternating solutions, such as operating system-level solutions.
  • . NET Framework 4 turned on the machine-wide security.
  • The shared and hosted Web applications can now run more securely without concerning about the CAS policies.
  • In . NET Framework 4.0, compilation warnings and runtime exceptions warn about obsolete CAS policy types and members either implicitly or explicitly.
  • However, warnings and errors are avoided by using < NetFx40_LegacySecurityPolicy > configuration element.

Question 68

Networks
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Describe in Detail

Essay▾

What is multicast routing?

Explanation

  • Sending a message to a group is called multicasting, and routing algorithm is called multicast routing.
  • Multicast communications are one-to-many or many-to-many- router forwards the received packets through several of its interfaces copying the data as necessary, and forward it to the receivers through several interfaces
  • Multicasting does not support reliable transport layer protocol such as TCP- source does not care about how many downstream receivers are receiving the data.
  • Multicast group identifies recipients interested in particular data stream represented by an IP address from a well-defined range.
  • Data sent to this IP address is forwarded to all members of the multicast group.
  • Routers between the source and recipients duplicate data packets and forward multiple copies wherever the path diverges.
  • Group membership information is used to calculate the best routers to duplicate the packets in the data stream.
  • Source sends data to a multicast group by setting the destination IP address of the datagram to be the multicast group address.
  • Any host can become a source and send data to a multicast group.
  • There are many different multicast protocols and modes of operation based on following principles:
    • A Multicast Group Membership Discovery protocol is used by receiving hosts to advertise their group membership to a local multicast router, For example, Internet Group Management Protocol (IGMP) for IPv4 and Multicast Listener Discovery (MLD) for IPv6.
    • Multicast Routing Protocol then enables routers to calculate the multicast distribution tree of receiving hosts. Protocol Independent Multicast (PIM) is the most important Multicast Routing Protocol.
Multicast Routing

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