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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
How do you find port number of a sql server?
In SQL Server 2005/2008 : Sql Server Configuration Manager -> Protocols -> TCP/IP -> IP Addresses -> TCP Port.
In SQL Server 2000 : Client Network Utility -> Select 'TCP/IP' from the enable protocols list and press 'Properties' button.
The default port is 1433.
Advantages and disadvantages of datagram packet switching?
A packet sniffer can also be used on the Internet to capture data traveling between computers. Internet packets often have very long distances to travel, passing through several routers that act like intermediate post offices. A packet sniffer might be installed at any point along the way. It could also be clandestinely installed on a server that acts as a gateway or collects vital personal information.
A packet sniffer is not just a hacker's tool. It can be used for network troubleshooting and other useful purposes. However, in the wrong hands, a packet sniffer can capture sensitive personal information that can lead to invasion of privacy, identity theft, and other serious eventualities.
What is a primary role of the physical layer in transmitting data on the network?
create the signals that represent the bits in each frame on to the media
What is the difference between access point and wireless bridge?
A wireless Access Point (AP) connects a group of wireless stations to an adjacent wired (Typically, Ethernet) LAN. An AP is like an Ethernet hub - except that a hub relays LAN frames only to other 802.3 stations, whereas an AP relays 802.11 frames to all other 802.11 or 802.3 stations in the same subnet. (In English: "it allows communication between wired and wireless..") A wireless router connects a group of wireless stations to an adjacent wired (Typically, Ethernet) LAN. A wireless router is a wireless AP combined with an Ethernet router. A wireless router forwards IP packets between your wireless subnet and any other subnet. Most routers also have a built-in firewall, and built-in Ethernet ports. (In English: same as an AP, but you can network different subnets or networks (Example: your home network and the Internet [Modem also required typically!] )
What are advantages of cloud computing?
Cloud computing is when data, programs, even access to printers and other devices are available through a server. The term "cloud" comes from the fact that the same cloud is accessible to many at the same time. It is meant to have everything all in one place that is available to all your computers/devices. In that sense it is better than a normal computer for storage.
Yes, you can. Phone line or cable is required for internet. If you want to use a router for local network only you do not need any other kinds of connections.
What is the purpose of the switch command switch port access vlan 99?
the switchport access vlan 99 command is used to designate a specific VLAN for a switch port, allowing you to control how traffic on that port is treated and segregated from traffic on other ports and VLANs in the network. This is a fundamental configuration step in building and managing VLANs within a network infrastructure.
Why is star topology the best topology?
Star topology is considered as best due to the following reasons
1.There is a central hub in which each individual system is connected.Suppose if one system fails it does not affect other system.This is the major advantage of star topology.
2.Secondly,it requires minimum cabling for the network
It depends, if your talking about myspace, it means your main picture. so like when you go to your home page and it says hello, (your name)! your defaault is the picture below it.
The noun default is an option that is selected automatically unless an alternative is specified. In a contest or election in which there is only one participant, that participant is said to win by default. If a loan or other legal financial obligation is unpaid, the debtor is in default and may be sued or criminally charged for fraud.
Does the s in https stands for secure socket layer?
It stands for secure socket layer. It means that the web site your on is safe from viruses or scam websites!
RJ stands for Registered Jack commonly used in Ethernet networking. The Ethernet cables has RJ45 connectors at both the ends.
Why is there a distance limitation in LAN?
Usually the limitation is to do with the wires. For example, the concept of attenutation is a biggie that network builders must at all times be considerate off. To be brief, a signal can only be sent so far down a line before it "dies".
The problem gets worse if your using wireless. Wireless can only be reliably used over short distances. But unlike wired, there is a lot of variables to consider with wireless. For example, if you sit maybe 15 ft away from your wireless and monitor the signal, then get your dog (hopefully a big dog) to stand in front of the router. You will notice a considerable drop in your signal because the dog is made up of so much fluid.
Wired connections don't have these pitfalls, though from what I can remember from college, I think if someone shines a UV light onto the wire - even though its coated in plastic - the UV will still disrupt the signal. This is something you would have to take into consideration if you were putting a LAN in a niteclub. Obviously wireless is out because off all the people (people are made up from water, the same as the dog) and the wires cant be exposed to any UV lights. That would be a complex LAN to design/construct.
What is the answer to packet tracer 11.5.1?
Dirección IP:
Máscara de subred
#
Subred
Primera dirección host
Última dirección host
Broadcast
0
198.133.219.0/24
198.133.219.1
198.133.219.14
198.133.219.15
1
198.133.219.16/24
198.133.219.17
198.133.219.30
198.133.219.31
2
198.133.219.32/24
198.133.219.33
198.133.219.46
198.133.219.47
3
198.133.219.48/24
198.133.219.49
198.133.219.62
198.133.219.63
4
198.133.219.64/24
198.133.219.65
198.133.219.78
198.133.219.79
5
198.133.219.80/24
198.133.219.81
198.133.219.94
198.133.219.95
6
198.133.219.96/24
198.133.219.97/24
198.133.219.110
198.133.219.111
7
198.133.219.112/24
198.133.219.1133
198.133.219.126
198.133.219.127
8
198.133.219.128/24
198.133.219.129
198.133.219.142
198.133.219.143
9
198.133.219.144/24
198.133.219.145
198.133.219.158
198.133.219.159
10
198.133.219.160/24
198.133.219.161
198.133.219.174
198.133.219.175
11
198.133.219.176/24
198.133.219.177
198.133.219.190
198.133.219.191
12
198.133.219.192/24
198.133.219.193
198.133.219.206
198.133.219.207
133
198.133.219.208/24
198.133.219.209
198.133.219.222
198.133.219.223
14
198.133.219.224/24
198.133.219.225
198.133.219.238
198.133.219.239
15
198.133.219.240/24
198.133.219.241
198.133.219.254
198.133.219.255
¿Cantidad máxima de subredes utilizables (incluida la subred 0)? 16
¿Cantidad de hosts utilizables por subred? 14
Tarea 1: Configuración de las opciones de configuración global del router de Cisco
Paso 1. Conecte físicamente los dispositivos.
Conecte la consola o el cable de consola al puerto de consola en el router. Conecte el cable de conexión cruzada entre la tarjeta de interfaz de red (NIC) de la computadora host y la interfaz Fa0/0 del router. Conecte un cable de conexión directa entre la interfaz Fa0/1 del router y cualquiera de las interfaces del switch.
Asegúrese de que se haya suministrado energía a la computadora host, al switch y al router.
Paso 2. Conecte la computadora host al router a través del terminal PT.
Haga clic en Host1 | Ficha escritorio | Terminal para iniciar el programa del terminal PT.
Deje todos los valores predeterminados cuando haga clic en terminal.
Paso 3. Configure las opciones de nombre de host de la configuración global.
¿Cuáles son los dos comandos que pueden usarse para salir del modo EXEC privilegiado?exit , ex
¿Qué comando directo se puede utilizar para ingresar al modo EXEC privilegiado? enable
Examine los distintos modos de configuración que se pueden ingresar con el comando configure? Terminal, memory, network
Tome nota de la lista de modos de configuración y la descripción. Desde el modo EXEC privilegiado, ingrese al modo de configuración global:
router# configure terminal router(config)#
¿Cuáles son los tres comandos que pueden usarse para salir del modo de configuración global y volver al modo EXEC privilegiado? control+z , exit, ex
¿Qué comando directo se puede emplear para ingresar al modo de configuración global?Configure
Establezca el nombre de host del dispositivo en Router1:
router(config)# hostname Router1 Router1(config)#
¿Cómo se puede eliminar el nombre de host? No hostname router1
Paso 4. Configure el banner MOTD.
En las redes de producción, el contenido del banner puede tener un impacto legal significativo en la organización. Por ejemplo, si el mensaje es "Bienvenido", un tribunal puede interpretar que se ha otorgado permiso para que se acceda sin autorización al router. El banner debe incluir información sobre la autorización, el castigo por el acceso no autorizado, el registro de la conexión y las leyes locales vigentes. En la política de seguridad corporativa se debe incluir una cláusula sobre los mensajes del banner. Cree un banner MOTD adecuado. Sólo los administradores del sistema de la compañía ABC tienen acceso autorizado. Se penaliza todo acceso no autorizado y se registra toda la información de la conexión.
Examine los diferentes modos de banner que se pueden ingresar. Tome nota de la lista de modos de banner y la descripción.
Router1(config)# banner ?
Elija un carácter de terminación que no se utilizará en el texto del mensaje. Configure el banner MOTD. El banner MOTD se muestra en todas las conexiones antes del aviso de inicio de sesión. Utilice el carácter de terminación en la línea en blanco para finalizar la entrada del MOTD:
Router1(config)# banner motd % Enter TEXT message. End with the character '%' *** Unauthorized access is prohibited and will be prosecuted. *** % Router1(config)#
¿Cuál es el comando de configuración global que se utiliza para eliminar el banner MOTD? No banner motd
Tarea 2: Configurar el acceso con contraseña al router Cisco
Las contraseñas de acceso se configuran para el modo EXEC privilegiado y punto de entrada de usuarios, como consola, aux y líneas virtuales. La contraseña del modo EXEC privilegiado es la contraseña más crítica, ya que controla el acceso al modo de configuración.
Paso 1: Configure la contraseña de EXEC privilegiado.
El IOS de Cisco admite dos comandos que permiten el acceso al modo EXEC privilegiado. Un comando, enable password, contiene criptografía débil y no debe usarse nunca si el comando enable secret está disponible. El comando enable secret usa un algoritmo hash de criptografía MD5 muy seguro. Cisco sostiene que "Hasta ahora, es imposible recuperar una contraseña secreta de enable a partir del contenido de un archivo de configuración (aparte de los obvios ataques de diccionario)". La seguridad con contraseña se basa en el algoritmo de contraseña y la contraseña. En los entornos de producción, se deben usar contraseñas seguras en todo momento. Una contraseña segura consta de nueve caracteres como mínimo, en minúsculas y mayúsculas, intercalados con números y símbolos. En un entorno de práctica de laboratorio usaremos contraseñas débiles. Establezca la contraseña del modo EXEC privilegiado en class. Router1(config)# enable secret class Router1(config)#
Paso 2: Configure la contraseña de consola.
Establezca la contraseña de acceso a la consola en cisco. La contraseña de consola controla el acceso de la consola al router.
Router1(config)# line console 0 Router1(config-line)# password cisco Router1(config-line)# login
¿Cuál es el comando que se utiliza para eliminar la contraseña de consola? No password cisco
Paso 3: Configure la contraseña de línea virtual.
Establezca la contraseña de acceso de línea virtual en cisco. La contraseña de línea virtual controla el acceso Telnet al router. En las primeras versiones de Cisco IOS, sólo se podían configurar cinco líneas virtuales, de la 0 a la 4. En las versiones de Cisco IOS más recientes, la cantidad ha aumentado. A menos que haya una contraseña Telnet, el acceso a esa línea virtual está bloqueado.
Router1(config-line)# line vty 0 4 Router1(config-line)# password ciscoRouter1(config-line)# login
Emita el comando exit. ¿Qué indicador mostró el router? ¿Cuál es el modo?Router1(config)# Router1(config-line)# exit
Emita el comando end. ¿Qué indicador mostró el router? ¿Cuál es el modo?
Router1#
Tarea 3: Configurar las interfaces del router Cisco
Paso 1: Configure la interfaz Fa0/0 del router con la última dirección disponible de la segunda subred. (Subred 1 en la tabla de direcciones).
Router1(config)# interface fa0/0 Router1(config-if)# description Connection to Host1 with crossover cable Router1(config-if)# ip address máscara de la direcciónRouter1(config-if)# no shutdown Router1(config-if)# end Router1#
Look for the interface to become active: *Mar 24 19:58:59.602: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
Paso 2: Configure la interfaz Fa0/1 del router con la última dirección disponible de la tercera subred. (Subred 2 en la tabla de direcciones). Router1(config)# interface fa0/1Router1(config-if)# description Connection to switch with straight-through cable Router1(config-if)# ip addressmáscara de la dirección Router1(config-if)# no shutdown Router1(config-if)# end Router1# Look for the interface to become active: *Mar 24 19:58:59,602: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Paso 3: Configure la computadora host.
Configure la computadora host para conectividad LAN. Recuerde que para acceder a la ventana de configuración LAN hay que hacer clic en la PC en la ficha Escritorio y luego en Configuraciones IP. Complete los siguientes campos:
Dirección IP: La primera dirección host en la segunda subred. (Subred 1 en la tabla de direcciones).
Máscara de subred: La máscara de subred
Gateway predeterminado: La dirección IP FastEthernet 0/0 en el Router1
Paso 4: Verifique la conectividad de la red.
Use el comando ping para verificar la conectividad de la red con el router. Si las respuestas del ping no son exitosas, siga una resolución de problemas de la conexión:
¿Qué comando IOS de Cisco puede usarse para verificar el estado de la interfaz? Show ip Interface brief
¿Qué comando de Windows se puede utilizar para verificar la configuración de la computadora host? Ipconfig
¿Cuál es el cable LAN correcto para conectar el host1 y el Router1? Conexio creuada
Tarea 4: Guardar el archivo de configuración del router
Cisco IOS se refiere al almacenamiento de la configuración de RAM como configuración en ejecución y al almacenamiento de la configuración NVRAM como configuración de inicio. Para que las configuraciones se mantengan luego de reiniciar o suministrar energía, la configuración RAM se debe copiar en la RAM no volátil (NVRAM). Esto no ocurre automáticamente; la NVRAM se debe actualizar manualmente luego de los cambios realizados.
Paso 1: Compare las configuraciones de router de RAM y de NVRAM.
Use el comando show de Cisco IOS para ver las configuraciones de RAM y de NVRAM.
Escriba un posible comando directo que mostrará el contenido de NVRAM. Muestre el contenido de la NVRAM. Si falta el resultado de la NVRAM, se debe a que no se ha guardado ninguna configuración:
Router1# show startup-config startup-config is not present Router1# Display the contents of RAM. Router1#show running-config
Utilice el resultado para responder las siguientes preguntas:
¿Qué tamaño tiene el archivo de configuración? 727 bytes
¿Cuál es la contraseña secreta de enable? Class
¿El banner MOTD contiene la información que ingresó antes? Si
¿Las descripciones de la interfaz contienen la información que ingresó antes? Si
Escriba un posible comando directo que mostrará el contenido de RAM.
Paso 2: Guarde la configuración de RAM en la NVRAM.
Se debe guardar la configuración manualmente en NVRAM para utilizarla la próxima vez que el router se encienda o recargue. Guarde la configuración de RAM en la NVRAM:
Router1# copy running-config startup-config Destination filename [startup-config]? Building configuration... [OK] Router1#
Tome nota de un comando directo posible que copie la configuración de RAM en la NVRAM. Revise el contenido de la NVRAM y verifique que la configuración sea la misma que la configuración en RAM.
Tarea 5: Configurar un switch Cisco
La configuración del switch Cisco IOS (afortunadamente) es similar a la configuración del router Cisco IOS. El beneficio de aprender los comandos de IOS es que son similares a muchos dispositivos y versiones de IOS diferentes
Paso 1: Conecte el host al switch.
Mueva la consola, o el cable de consola, al puerto de la consola en el switch. Asegúrese de que se haya aplicado energía al switch. En Hyperterminal, presione Ingresar hasta que el switch responda.
Paso 2. Configure las opciones de nombre de host de la configuración global.
Dependiendo del modelo del router y de la versión de IOS, su configuración puede verse ligeramente diferente. Sin embargo, no debe haber contraseñas configuradas. Si su router no tiene una configuración por defecto, pida al instructor que elimine la configuración. Desde el modo exec usuario, ingrese al modo de configuración global:
Switch> en Switch# config t Switch(config)# Set the device hostname to Switch1.Switch(config)# hostname Switch1 Switch1(config)#
Paso 3: Configure el banner MOTD.
Cree un banner MOTD adecuado. Sólo los administradores de sistema de la Compañía ABC tienen acceso autorizado; el acceso no autorizado será penalizado y toda la información de conexión será registrada. Configure el título MOTD. El título MOTD aparece en todas las conexiones antes de la petición de inicio de sesión. Use el carácter de finalización en una línea en blanco para finalizar la entrada MOTD. Para obtener ayuda, revise el paso similar para configurar un título MOTD de router.
Switch1(config)# banner motd % Advertencia de acceso autorizado solamente.%
Paso 4: Configure la contraseña de EXEC privilegiado.
Establezca la contraseña de EXEC privilegiado en class. Switch1(config)# enable secret class Switch1(config)#
Paso 5: Configure la contraseña de consola.
Establezca la contraseña de acceso a la consola en cisco.
Switch1(config)# line console 0 Switch1(config-line)# password cisco Switch1(config-line)# login
Paso 6: Configure la contraseña de línea virtual.
Establezca la contraseña de acceso de línea virtual en cisco. Hay 16 líneas virtuales que pueden configurarse en un switch del IOS de Cisco, de 0 a 15.
Switch1(config-line)# line vty 0 15 Switch1(config-line)# password ciscoSwitch1(config-line)# login
What protocols at other layers of the OSI model does ping use?
Layer 3 of the OSI model.
An ICMP header follows the IP header of the IP packet.
4 elements of computer system?
A main memory, which stores both data and instructions: an arithmetic and logic unit (ALU) capable of operating on binary data; a control unit, which interprets the instructions in memory and causes them to be executed; and input and output (I/O) equipment operated by the control unit.
Can fiber optic cable be connected to a coaxial cable?
a basic cable system works as follows information is received via satellite from the information providers also known as a channel in what is known as a head end where they process the signal and insert it into qualms which leave the head end on fiber optic cable by laser till it gets to the neighborhood or neighborhoods where there are subscribers. the fiber optics then hit what is called a node. at the node a fiber optical receiver changes it from light into db which is then sent out on distribution style coaxial cable usually a plastic based coating quantum reach style cable or qr cable. it then hits an amplifier where it is jumped up to about 40 db give or take as it travels down the street. where there is a house there is a tap in the qr cable, which is where the coaxial cable people are most familiar with starts
How do you find your wep key on a sky router?
The network administrator should have the information at hand. If you are the administrator, contact the hardware vendor for assistance.
What are the differences between lan man wan pan?
The world of computer networking is filled with acronyms and these four happen to be in order. Can you guess how?
OK, that's pretty easy. It's by distance from near to far. The only one of these that hasn't been around for ages is PAN or Personal Area Network. PANs include Bluetooth, USB, UWB (Ultra Wide Band) and FireWire. A personal area network is intended for your personal use to interconnect electronic devices you are using. Bluetooth is emerging as the king of wireless personal area networks. If your cell phone and laptop computer both have Bluetooth enabled, you can get Internet access for your computer via Bluetooth from your cell phone that is connected to an EV-DO or GPRS data network.
Most everybody has a LAN or Local Area Network now. There once were many protocols for connecting computers, printers, and telecommunications networks within the corporate environment. Eventually everyone migrated to Ethernet with TCP/IP. That has gelled to the point where every new technology had better have IP connectivity, at least at the edges. The standardization around the Internet Protocol and Ethernet has promoted an economy of scale to the point where you can buy a 10/100 Mbps Network Interface Card at Wal-Mart for under ten bucks.
Every PC and many printers now come with Ethernet ports standard. Most portable devices support the Wireless version of Ethernet, Wi-Fi, which is also termed a Local Area Network. A LAN is intended for use within a room, building or area. WiFi's range of around 300 ft. puts it into this category.
Within an office or corporate campus, networking revolves around the LAN or LANs running on CAT5, CAT5e or CAT6 copper wiring with some spans of fiber optic cable and some wireless LANs. When you leave the LAN, you enter the world of MANs and WANs.
MAN is Metropolitan Area Network. It's intended for use within a city. A typical example is a SONET Synchronous Optical Network that is set up as a pair of fiber optic rings within the business district of a city. The reason for a pair is to provide redundancy in case one of the rings fail. The other takes over within 50 msec, perhaps so fast the outage isn't even noticed by many users. You get to the MAN with an access network connection. That may be an OC3 or OC12 fiber optic link or a T1 or T3 service.
Note that SONET is a different protocol than Ethernet. With some fancy bit handling, Ethernet can be formatted to be carried by SONET, T1, T3, or other digital networks. The Ethernet packets can be split up to fit the requirements of the carrier and reassembled at the other end.
Going cross-country you are using a long distance carrier called a WAN or Wide Area Network. A WAN can connect MANs together or simply connect a group of individual locations. The Internet is an enormous WAN. You can get WAN service from a variety of competitive carriers with speeds from T1 at 1.5 Mbps up to OC48 at 2.5 Gbps or even OC192 at nearly 10 Gbps.
Most WANs are TDM or Time Division Multiplexing based because that is the standard adopted by the telephone carriers that first implemented them. Since much data is now packet based using the IP standard, carriers are now offering native IP based networking connections in many areas. That means that your LAN data never changes protocol. It leaves your router as Ethernet, traverses an Ethernet WAN, and hooks to another LAN some distance away. To the IT manager it all looks like one big corporate LAN, even though a common carrier provides the link between sites.
What is Advantage and disadvantage of computer network?
check out www.hack-ur-admin.blogspot.com
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The more devices you have the more need of a "network". If you have a DSL/Cable connection, then a Router gives you another "Firewall" between you and the internet (or if wireless, from your unknown neighbor). If you just have two computers and a "dial-up" internet it's probably not worth it. It's just when you start adding stuff.
Advantage is,
If you have a Router doing all the leg work then it's that much less you have to do. With a Wireless Router, you don't have to buy a wireless adapter for the computer to stream to another wireless computer or to a wireless TV, Blueray, etc. You'll have a "hardware" firewall which is better then none or a software version. You don't have to keep hooking up a cable every time you want to transfer files to the other computer. (if you don't have wireless computers). Keeps you from downloading the same app twice. It "transfers" files to another computer a 100 times faster then having to download the same file again off the internet onto another computer.
Disadvantage is,
You have to set everything up the first time. "Might" be hard for Non-geeks.
To monitor network devices, you can use spiceworks or 10-Strike Network Monitor.
To monitor internet activities, I would recommend WFilter Enterprise.
Example of Business proposal for internet cafe?
An example of a business proposal for an internet cafe might include having an hourly rate for internet usage. The proposal would need to layout exactly what the plans for the internet cafe would be, how it would run, the rates, expenditures, and revenue projections.
a modem is essentaly a phone that is in your computer that alows you to conect to a network like a internet service provider over the phone line.
What is the hardware device that connects your computer to the internet with a wireless connection?
Computer > Network Adapter > Router > ISP > Internet
Why collision is an issue in a random access protocol?
In random access methods, there is no access control (as there is in controlled access methods) and there is no predefined channels (as in channelization). Each station can transmit when it desires. This liberty may create collision.
