1.Explain difference between      baseband and broadband transmission?

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      In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.


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        Redirector is software that intercepts file or prints I/O requests and translates the into network requests. This comes under presentation layer.


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      The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.


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       A resource record is an entry in a name server’s database. There are several types of resource records used, including name-to-address resolution information. Resource records are maintained as ASCII files.


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       External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is not system-dependent.


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       A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.


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       Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user’s ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.


8.Explain a Management Information Base (MIB)?

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       A Management Information Base is part of every SNMP-managed device. Each SNMP agent has the MIB database that contains information about the device’s status, its performance, connections, and configuration. The MIB is queried by SNMP




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       The using of IMAP to access your mailbox has advantages overPOP3 and the difference of their working mechanism.

Mechanism of POP3
•Since email needs to be downloaded into desktop PC before being displayed, you may have the following problems for POP3 access:
You need to download all email again when using another desktop PC to check your email.
May get confused if you need to check email both in the office and at home.
The downloaded email may be deleted from the server depending on the setting of your email client.
•All messages as well as their attachments will be downloaded into desktop PC during the ‘check new email’ process.
•Mailboxes can only be created on desktop PC. There is only one mailbox (INBOX) exists on the server.
•Filters can transfer incoming/outgoing messages only to local mailboxes.
•Outgoing email is stored only locally on the desktop PC.
•Messages are deleted on the desktop PC. Comparatively, it is inconvenient to clean up your mailbox on the server.
•Messages may be reloaded onto desktop PC several times due to the corruption of system files.

Mechanism of IMAP
•Since email is kept on server, it would gain the following benefits for IMAP access:
No need to download all email when using other desktop PC to check your email.
Easier to identify the unread email.
•A whole message will be downloaded only when it is opened for display from its content.
•Multiple mailboxes can be created on the desktop PC as well as on the server.
•Filters can transfer incoming/outgoing messages to other mailboxes no matter where the mailboxes locate (on the server or the PC).
•Outgoing email can be filtered to a mailbox on server for accessibility from other machine.
•Messages can be deleted directly on the server to make it more convenient to clean up your mailbox on the server.
•The occurrence of reloading messages from the server to PC is much less when compared to POP3.


10.What is ERD(Emergency Repair Disk)?

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       To create an ERD:

1. Click Start, point to Programs, point to Accessories, point to System Tools, and then click Backup.
2. On the Tools menu, click Create an Emergency Repair Disk.
You can use the ERD for the following repair functions:
• Inspect and repair the startup environment.
• Verify the Windows 2000 system files and replace missing or damaged files.
• Inspect and repair the boot sector.
When you attempt to repair Windows 2000, it asks if you have an ERD diskette, if you do not have the diskett, press L and thecomputer attempts to locate your Windows 2000 installation to perform repairs. This process looks for the Boot.ini file on your computer partition and reads the ARC paths to your operating system(s). The computer then attempts to load the following hive for each ARC path:
%systemroot%\System32\Config\Software
This attempt finds which installation versions matches the installation CDROM used to do the repair.
If the Boot.ini file cannot be read, or the software hive is corrupt, the repair is not able to proceed. At this time, you must have a ERD diskette containing a valid Setup.log file for that computer before repairs are possible.
The registry hives saved during setup are in the following folder:
%systemroot%\repair
The registry hives are used during a FAST repair only, otherwise you need to use Recovery Console to manually copy a more recent registry hive saved by NTbackup in the following folder:
%systemroot%\repair\regback


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       DHCP (Dynamic Host Configuration Protocol) allows yourcomputer to automatically obtain a fully functional IP address from the central RPI DHCP server. Every time you boot up your computer, your operating system retrieves a new IP address. DHCP is the default network configuration for most operating systems. If however you need to set up DHCP again, follow the instructions on the various Network Configurations webpages for your specific operating system. Static IP is a manual way of obtaining an IP address for your computer. The IP address is predetermined and always the same. A static IP address can be obtained for free from the VCC Help Desk by filling out a short form. There are a few advantages and disadvantages to using a static IP.
Advantages:
Your IP address remains the same so that you can run Internetservices that require your IP address to remain the same in order for them to work properly (ie. Web Server, FTP Server).
If, for some reason, the RPI DHCP server is having difficulties handing out IP address, you will still be able to access the web, since your IP is predetermined.
Disadvantages:
You will only be able to effectively use your static IP address from your place of residence. You will be unable to use the web from other places on campus.
Configuring the network settings on your computer is more difficult for static IP than for DHCP, since DHCP is automatic and static IP is manual.



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      The Recovery Console is a feature of the Windows 2000 and Windows XP operating systems. It provides the means for administrators to perform a limited range of tasks using a textual user interface. As its name suggests, its primary function is to enable administrators to recover from situations where Windows does not boot as far as presenting its graphical user interface.


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       Although hubs and switches both glue the PCs in a network together, a switch is more expensive and a network built with switches is generally considered faster than one built with hubs. When a hub receives a packet (chunk) of data (a frame in Ethernet lingo) at one of its ports from a PC on the network, it transmits (repeats) the packet to all of its ports and, thus, to all of the other PCs on the network.� If two or more PCs on the network try to send packets at the same time a collision is said to occur.� When that happens all of the PCs have to go though a routine to resolve the conflict.� The process is prescribed in the Ethernet Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.� Each Ethernet Adapter has both a receiver and a transmitter. If the adapters didn’t have to listen with their receivers for collisions they would be able to send data at the same time they are receiving it (full duplex). Because they have to operate at half duplex (data flows one way at a time) and a hub retransmits data from one PC to all of the PCs, the maximum bandwidth is 100 Mhz and that bandwidth is shared by all of the PC’s connected to the hub. The result is when a person using a computer on a hub downloads a large file or group of files from another computer the network becomes congested.� In a 10 Mhz 10Base-T network the affect is to slow the network to nearly a crawl.� The affect on a small, 100 Mbps (million bits per scond), 5-port network is not as significant.
An Ethernet switch automatically divides the network into multiple segments, acts as a high-speed, selective bridge between the segments, and supports simultaneous connections of multiple pairs of computers which don’t compete with other pairs of computers for network bandwidth.� It accomplishes this by maintaining a table of each destination address and its port.� When the switch receives a packet, it reads the destination address from the header information in the packet, establishes a temporary connection between the source and destination ports, sends the packet on its way, and then terminates the connection. Picture a switch as making multiple temporary crossover cable connections between pairs of computers (the cables are actually straight-thru cables; the crossover function is done inside the switch).� High-speed electronics in the switch automatically connect the end of one cable (source port) from a sending computer to the end of another cable (destination port) going to the receiving computer on a per packet basis.� Multiple connections like this can occur simultaneously.� It’s as simple as that. And like a crossover cable between two PCs, PC’s on an Ethernet switch do not share the transmission media, do not experience collisions or have to listen for them, can operate in a full-duplex mode, have bandwidth as high as 200 Mbps, 100 Mbps each way, and do not share this bandwidth with other PCs on the switch.� In short, a switch is “more better.”
      


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       One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

1. What is an Object server?

With an object server, the Client/Server application is written as a set of communicating objects. Client object communicate with server objects using an Object Request Broker (ORB). The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together.

2. What is a Transaction server?

With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request/reply message. The SQL statements either all succeed or fail as a unit.

3. What is a Database Server?

With a database server, the client passes SQL requests as messages to the database server. The results of each SQL command are returned over the network. The server uses its own processing power to find the request data instead of passing all the records back to the client and then getting it find its own data. The result is a much more efficient use of distributed processing power. It is also known as SQL engine

Q: What are the seven layers of the OSI model?

A: The layers are physical, data link, network, transport, session, presentation, and application layers.

Q: In the TCP client-servel model, how does the three-way handshake work in opening connection?

A: The client first sends a packet with sequence "x" to the server. When the server receives this packet, the server will send back another packet with sequence "y", acknowledging the request of the client. When the client receives the acknowledgement from the server, the client will then send an acknowledge back to the server for acknowledging that sequence "y" has been received.

Q: What is the purpose of exchanging beginning sequence numbers during the the connection in the TCP client-server model?

A: To ensure that any data lost during data transfer can be retransmitted.

Q: How does Asynchronous Transfer Mode (ATM) work?

A: ATM works by transmitting all traffic in small, fixed-sized cells. These small, fixed-size cells reduces queuing delay and can be switched quickly. ATM fits into layer 2 of the OSI model and provides functions for framing and error correction. At the port interface, ATM switches convert cells into frames, and vice versa. ATM provides Quality of Service and traffic shaping.

Q: Given a Class B Network with subnet mask of 255.255.248.0 and a packet addressed to 130.40.32.16, what is the subnet address?

A: Take the 2 addresses, write them in binary form, then AND them. The answer is 130.40.32.0

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