Difference among Point to Point,Broadcast and Non-broadcast multiaccess networks

Point-to-point:
                      A point-to-point network joins a single pair of routers. A T1 serial line configured with a link-layer protocol such as PPP or High-Level Data Link Control (HDLC) is an example of a point-to-point network.
Broadcast:
                     A multiaccess broadcast network, such as Ethernet.
Nonbroadcast multiaccess (NBMA):
                     A network that interconnects more than two routers but that has no broadcast capability. Frame Relay, ATM, and X.25 are examples of NBMA networks.

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Command to enable OSPF Routing protocol on Router interface mode

Here is a Command to enable OSPF routing protocol on a router interface mode for that particular interface
as-
Router(Config-if)#ip ospf <process-id> area <area-id> [secondaries none].

Ex.
Router(Config-if)#ip ospf 100 area 0 secondaries none
 
-->Here secondaries none is optional which prevent other secondary ip address on the interface being advertise.

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Why We used areas in OSPF routing protocol?

To reduce the SPF calculations, link-state routing protocols can partition networks into sub-domains called areas.
 In small networks, the web of router links is not complex, and paths to individual destinations are easily deduced. However, in large networks, the resulting web is highly complex, and the number of potential paths to each destination is large. Therefore, the SPF calculations comparing all these possible routes can be very complex and can take significant time. The CPU and memory resources on an OSPF router can also be overburdened in a heavily populated OSPF network.

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How to create a TCL script in router for ping ?

Router ios version 12.3 or higher version are support TCL script on router. To write a simple TCL script for ping different interfaces or devices use that code----

foreach address

{

x.x.x.x

x.x.x.x

x.x.x.x

.

.

}

{ping $address}

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How to configure GNS3 to a virtual box client.

To configure the GNS3 with a virtual box client follow these steps-
1.-->  Start the gns3 and drag a router from the list and drop it to the working windows.
2.-->  Like router also drag a cloud and drop in working window.

3.--> Now Double click on cloud and select a C1 menu on the left hand list .
         after that select NIO ethernet tab.Here is the drop down list in which select a  virtual
        Box host only network. add this and apply the settings.

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What is diffrence between DHCP and BOOTP ?

    DHCP stand for     Dynamic host configuration protocol.
    BOOTP stand for   BootStrap protocol.
  Major differences between them as follows--

  1.   BOOTP was designed for manual pre-configuration of the host information in a server database, while DHCP allows for dynamic allocation of network addresses and configurations to newly attached hosts. When a BOOTP client requests an IP address, the BOOTP server searches a predefined table for an entry that matches the MAC address for the client. If an entry exists, the corresponding IP address for that entry is returned to the client. This means that the binding between the MAC address and the IP address must have already been configured in the BOOTP server.

 2.   DHCP allows for recovery and reallocation of network addresses through a leasing mechanism. Specifically, DHCP defines mechanisms through which clients can be assigned an IP address for a finite lease period. This lease period allows for reassignment of the IP

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How to execute a privilege mode command on configuration mode in Router

When we execute a privilege command like show, clear commands on global mode of router .Then it show an error message

Router(config)#show ip int

                ^

% Invalid input detected at '^' marker.

Router(config)#

To solve out this problem do command it used to execute privilege commands on global mode.

Router(config)#do show ip int brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        10.1.1.1        YES manual up                    down

FastEthernet0/1        unassigned      YES unset  administratively down down

Vlan1                  unassigned      YES unset  administratively down down

Router(config)#

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How to worms are infects to networks what are the steps are used to infect network?

Worms are a particularly dangerous type of hostile code. They replicate themselves by independently exploiting vulnerabilities in networks. Worms almost always slow down networks.

   Hackers and Attackers use five basic phases of attack, regardless of whether a worm or virus is employed-

1.           Probe -The goal is to find computers that can be subverted. Internet Control Message Protocol (ICMP) ping scans are used to map networks. Then the application scans and identifies operating systems and vulnerable software. Hackers can obtain passwords using social engineering, dictionary attack, brute-force attack, or network sniffing.

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An Intresting story about Trojan Horse

The term Trojan Horse originated from Greek mythology. Greek warriors offered the people of Troy (Trojans) a giant hollow horse as a gift. The Trojans brought the giant horse into their walled city, unaware that it contained many Greek warriors. At night, after most Trojans were asleep, the warriors burst out of the horse and overtook the city.A Trojan Horse in the world of computing is malware that carries out malicious operations under the guise of a desired function. A virus or worm could carry a Trojan Horse. A Trojan Horse contains hidden, malicious code that exploits the privileges of the user that runs it. Games can often have a Trojan Horse attached to them. When running the game, the game works, but in the background, the Trojan Horse has been installed on the user's system and continues running after the game has been closed.

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How to change the ip address in linux

To change the IP address of a network device in linux can use terminal or GUI. here  change by  using the terminal mode with  the help of few commands .
To reach the command terminal follow instructions -

-> Goes to Applications ---> Accessories ---> Terminal.
-> To check the IP address enter command 

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How to connect two computers via lan and share data ?

We connect two computer via lan and also share the data . the step for this as :-

To connect two computers via lan need a lan Ethernet cable .

First connect two computer via Ethernet cable  for this insert the cable ends in lan card port in both computers.

First select a computer and perform this procedure-

Goes to control panel -> network and sharing center  -> local area connection.

Right click on it and select properties.

In which find internet protocol version 4 (TCP/IPv4) and double click on it.

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First Worm Infection

The Robert Morris created the first Internet worm with 99 lines of code. When the Morris Worm was released, 10% of Internet systems were brought to a halt. Robert Morris was charged and received three years probation, 400 hours of community service, and a fine of US$10,000.

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How to start ping and ipconfig commands on Window xp/7.

Steps to start these cmmands:

----> First Go to c:/windows/system32 .

---->check ipconfig and ping command exsist.

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