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Computer Networking
Computer networks are collections of computers which are connected together in order to communicate and transfer information. Questions about computer networks, networking protocols, and how to set them up belong here.
18,810 Questions
What is asynchronous data transfer?
Synchronous= syn+ chrono = togetherness in time. So, the two or more communication system agree to be together in time to the change in signals or data.That means they should share the same clock speed.
In asynchronous systems, the clock information is contained in the data block itself in the form of start and stop bits and hence the receiving system can adjust itself to that speed,any speed. Async systems are serial in nature and the former can be either serial or are mostly parallel.
What is the most common central device used today to connect computers to a network?
Routers, Switches, Modems, and Hubs, but mostly Routers
when we decide to form a network such a shortest path have to establish for data transmitting,different type of topology we have to use.
for eg:-if i hav one server or hub or a switch(one centralize device)and 15 clients
to connect ,then there are various ways to connect them according to our need...
topologies are of type:
!)star-when we need all the terminal attched to one central decice
2)ring-whn we need all terminals connect to each other also
2)mesh-combination of ring and star
4)bus-when we dont need centrliez device,onle connect one terminal to another and so on
5)hybrid-combination of all topology
(If that's the question being asked...) Indexing in a database system or a simple file-oriented system is used to make different records easier to access quickly. An index would be used to find data based on a certain key value quickly by going directly to the first record with that key, instead of searching the entire database or file. Indices are also handy for linking one file to another, such as with related information in different tables in a relational database system.
What are port numbers explain?
A port number is a kind of address within a computer. It helps distinguish different services on a server. Thus, any data that goes to port 80 (TCP) will be processed by the Web server; data for other ports gets sent to other applications.
On the client side, the port number helps separate different "conversations". For example, if I load different Web pages at the same time, in my browser, one might be assigned to port 1024, the next to port 1025, etc. This is the origin port; the destination port is still port 80. But when data comes back from the server, my computer will receive it at port 1024, or port 1025, and thus know to which file the information must be added.
A port number is a kind of address within a computer. It helps distinguish different services on a server. Thus, any data that goes to port 80 (TCP) will be processed by the Web server; data for other ports gets sent to other applications.
On the client side, the port number helps separate different "conversations". For example, if I load different Web pages at the same time, in my browser, one might be assigned to port 1024, the next to port 1025, etc. This is the origin port; the destination port is still port 80. But when data comes back from the server, my computer will receive it at port 1024, or port 1025, and thus know to which file the information must be added.
A port number is a kind of address within a computer. It helps distinguish different services on a server. Thus, any data that goes to port 80 (TCP) will be processed by the Web server; data for other ports gets sent to other applications.
On the client side, the port number helps separate different "conversations". For example, if I load different Web pages at the same time, in my browser, one might be assigned to port 1024, the next to port 1025, etc. This is the origin port; the destination port is still port 80. But when data comes back from the server, my computer will receive it at port 1024, or port 1025, and thus know to which file the information must be added.
A port number is a kind of address within a computer. It helps distinguish different services on a server. Thus, any data that goes to port 80 (TCP) will be processed by the Web server; data for other ports gets sent to other applications.
On the client side, the port number helps separate different "conversations". For example, if I load different Web pages at the same time, in my browser, one might be assigned to port 1024, the next to port 1025, etc. This is the origin port; the destination port is still port 80. But when data comes back from the server, my computer will receive it at port 1024, or port 1025, and thus know to which file the information must be added.
How many layers are in the OSI model?
The OSI 7 layer model descibes the theoretical levels of networking on a computer Layer 1 Physical Layer - actual network cable and connectors
Layer 2 Data Link Layer - network address (MAC) and packet switching
Layer 3 Network Layer - Internet Protocol (IP) - addressing and packet routing
Layer 4 Transport Layer - Transmission Control Protocol (TCP) - packet sequencing & error correction
Layer 5 Session Layer - Connection control for repeated send/receive (a session)
Layer 6 Presentation Layer - presenting information to application in correct format
LAyer 7 Application Layer - actual display/control of information, layout etc. for two computers to communicate -example chat program the following would occur user types into a chat program on computer A (7)
application accepts input and decides what to do with it (6)
a connection is requested to send to computer B (5)
the message is broken into pieces and encpsulated within a packet (which includes the address to send to and the address from which it came) Packets are given a sequence number(4)(3)
Packet sent across the network using the addressing information to determine where to go to(3)(2)(1) on Computer B the revers happens - packet is put back together - addressing information is removed and eventually displayed on the screen.
How do you connect three routers in packet tracer?
To connect multiple routers in PacketTracer 5.2, first select the "routers" section in the bottom left hand corner. From there, you can drag two routers from the pane to the right onto the working area (the large white space on your screen). Once both routers are on the screen, click "connections" (the lightning bolt) in the lower left, and click on "Automatically choose connection type" (the first one) OR "Copper crossover" (the fourth one). You will get a cursor that looks somewhat like a taser gun. Click once on each router, and you will see a cable created between them with a red dot on either end. You can now configure and power on both routers, and they will be able to communicate.
Be sure when configuring both routers that you go into the Interface section and check that at least one FastEthernet port is set as "ON", so that the routers can communicate.
How do you clear DNS cache on the DNS server?
- Open DNS.
- In the console tree, click the applicable DNS server.
Where?
- DNS/applicable DNS server
- On the Action menu, click Clear Cache.
Notes
- To perform this procedure, you must be a member of the Administrators group on the local computer, or you must have been delegated the appropriate authority. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure.
- To open DNS, click Start, click Control Panel, double-click Administrative Tools, and then double-click DNS.
- Open Command Prompt.
- Type the following command and then press ENTER:
Dnscmd ServerName /clearcache
encryption key
Which command will display RIP activity as it occurs on a router?
"debug ip rip" is the correct answer. Use to display information on selected RIP events. This command has many keywords that allow you to specify a variety of RIP events. You can set the level of severity for the events you want displayed; specify the desired descriptive term or a corresponding number (0-7). You can set the verbosity of the messages you want displayed: low, medium, high. Example host1#debug ip rip events Use the no version to cancel the display of any information on the designated variable.
The subnet mask. The subnet mask consists of a certain number of ones, followed by a certain number of zeroes (in binary). The ones tell you how many bits in an IP address make up the network part; the zeroes are for the host.
The subnet mask. The subnet mask consists of a certain number of ones, followed by a certain number of zeroes (in binary). The ones tell you how many bits in an IP address make up the network part; the zeroes are for the host.
The subnet mask. The subnet mask consists of a certain number of ones, followed by a certain number of zeroes (in binary). The ones tell you how many bits in an IP address make up the network part; the zeroes are for the host.
The subnet mask. The subnet mask consists of a certain number of ones, followed by a certain number of zeroes (in binary). The ones tell you how many bits in an IP address make up the network part; the zeroes are for the host.
What is relation between IEEE and OSI layer?
The OSI (Open Systems Interconnect) 7-layer model is based, in-part, on standards published by the IEEE (Institute of Electrical and Electronics Engineers). For example, IEEE standard 802.3 describes Ethernet. In the OSI model, the 802.3 standard exists at layers 1 and 2. ANSWER IEEE is a standards organization to which many hardware and software suppliers both contribute to and agree to use 'standardized' techniques. Ethernet is but only ONE of the many standards, and the OSI is only one of the usage standards.
What three statements describe a DHCP discover message?
1. The destination IP address is 255.255.255.255
2. The message comes from a client seeking an IP address
3. All host receive the message, but only a DHCP server replies
What is the concept of Framing in data link layer?
The data link layer packs bits which have been moved by the Physical Layer, into frames, so that each frame is distinguishable from another whiles being transmitted to destination.
A point-to-point connection between two computers or devices consists of a wire in which data is transmitted as a stream of bits. However, these bits must be framed into discernible blocks of information. Framing is a function of the data link layer which provides a way for a sender to transmit a set of bits that are meaningful to the receiver. Ethernet, token ring, frame relay, and other data link layer technologies have their own frame structures. Frames have headers that contain information such as error-checking codes.
There are three different types of framing, each of which provides a way for the sender to tell the receiver where the block of data begins and ends:
- Byte-oriented framing Computer data is normally stored as alphanumeric characters that are encoded with a combination of 8 bits (1 byte). This type of framing differentiates one byte from another. It is an older style of framing that was used in the terminal/mainframe environment. Examples of byte-oriented framing include IBM's BISYNC protocol.
- Bit-oriented framing This type of framing allows the sender to transmit a long string of bits at one time. IBM's SDLC (Synchronous Data Link Control) and HDLC (High-level Data Link Control) are examples of bit-oriented protocols. Most LANs use bit-oriented framing. There is usually a maximum frame size. For example, Ethernet has a maximum frame size of 1,526 bytes. The beginning and end of a frame is signaled with a special bit sequence (01111110 for HDLC). If no data is being transmitted, this same sequence is continuously transmitted so the end systems remain synchronized.
- Clock-based framing In a clock-based system, a series of repetitive pulses are used to maintain a constant bit rate and keep the digital bits aligned in the data stream. SONET (Synchronous Optical Network) is a synchronous system in which all the clocks in the network are synchronized back to a master clock reference. SONET frames are then positioned within the clocked stream.
The advantage of using frames is that data is broken up into recoverable chunks that can easily be checked for corruption. If a problem occurs during the transmission and some frames get corrupted, only the lost frames will be retransmitted, and not the entire set of data.
The usual approach and prime purpose of the Data Link Layer is to break the bit stream up into discrete frames for the purpose of Error Detection or Correction
By Louis Khim Burns
What is the maximum number of channels that a single T1 can contain?
544,638,374,283,290,000,000,000,000,000,000. te he!
What is your primary DNS server and your secondary DNS sever?
Hello,
This will depend on where you choose to host your DNS. If you have not modified your DNS (or name) servers, then chances are that your DNS is currently hosted with your domain registrar.
You can check your name servers with the Linux command:
dig +short ns <domain.com>
You can also get this information from a DNS tools site such as:
http://network-tools.com
Good Luck!
Ryan Bradley
Junior Server Engineer
HostMySite.com
http://hostmysite.com/?utm_source=bb
What are authoritative dns server and none authoritative dns server?
authoritative dns server is server that has own databases that has name resolution for the clients that for resolve from name to ip address and for ip address to name.
non-authorititative dns server is server that forward request of dns client to authoritative dns server for resolve.
What is the role of server in client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
what is client server architecture?
A computer network is defined as two or more computers connected via software and hardware so that they can communicate with each other. Ultimately, a computer network enables the exchange of data among computers.
You would use a cat5 (usually called ethernet) for connecting maybe a computer to a switch. Or connecting a server to a router/firewall... Its probably one of the most common network cables you could use, well for home and small to medium sized buisnesses anyway.
