3i Infotech Placement: Sample Questions 1146 - 1147 of 1245
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Question 1146
Explanation
- Thrashing is little progress in a computer system because memory or other resources are either exhausted or limited to perform needed operations.
- Caused in virtual memory schemes when the processor spends most of its time swapping pages- due to page faults.
- It is caused when pages in memory refer other pages.
- The large “working set” of active processes cannot be all accommodated in the real memory.
- Virtual memory systems allows placing some pages on virtual memory- only bringing required page on demand into the RAM.
- A thrashing system is either a very slow system might come to a halt.
- Generally occurs when enough frames are not allocated to a process than are needed.
Two Ways to Prevent Thrashing
- Instruct mid-term scheduler to swap out some of the process to recover from thrashing
- Instructing the dispatcher not to load more processes after a threshold
Question 1147
Explanation
- NETBIOS:
- Programming interface allowing I/O requests to be sent to and received from a remote computer.
- Hides the networking hardware from applications.
- Supports small to medium networks providing transport and network layer support.
- Fast and small and works well for the DOS operating system.
- System wide methods of resolving NETBIOS names to IP address are:
- b-node - Broadcast node
- p-node - Point-to-point node queries an NBNS name server to resolve addresses.
- m-node - First uses broadcasts, then falls back to querying an NBNS name server.
- h-node - The system first attempts to query an NBNS name server, then falls back to broadcasts if the name server fails.
- NETBEUI:
- NETBEUI is NETBIOS extended user interface.
- A transport protocol designed by Microsoft and IBM for small subnets responsible for data transport.
- Handles all the frame formatting not handled by NETBIOS.