Showing posts with label Networking. Show all posts
Showing posts with label Networking. Show all posts

classes of IP address


Q. 1  Explain the classes of IP address

Answer: IP addresses are organized into classes. For convenience of humans, IP addresses are expressed in the decimal format. Every number in each class is represented as binary to computers.
The four numbers in an IP address are known as ‘octets’. Each of them has eight bit positions. The octets are divided into two sections: Net and Host. The first octet represents Net for identifying the network and the Host contains the last octet. There are five IP classes.
Class A: The class A is used for very large networks. There are 1 to 126 are part of this class. That means there are 126 Class A networks. Class A networks accounts for half of the total available IP addresses.
Class B: It is used for medium size networks. The IP address with a first octet from 128 to 191 is part of this class. Class B networks have a first bit value of 1 and a second bit value of 0 in the first octet.
Class C: Class C is used for small to middle size networks. IP address with a first octet starts from 192-223. Class C networks have a first bit value of 1, second bit value of 1 and a third bit value of 0 in the first octet.
Class D: It has first, second and third bit value as 1 and the fourth bit as 0. The other 28 bits are used for identifying the group of computers which is intended for multicast messages.
Class E: Class E is used for identification purpose. The four bits value is 1. The other 28 bits are used for identifying the group of computers which is intended for multicast messages.

User Datagram Protocol

Q.  What is the User Datagram Protocol (UDP)?

Answer: User datagram protocol allows computer applications to send messages as datagram packets from source to destination on an Internet Protocol, with out using prior communications for setting up special transmission paths. An unreliable service is provided by UDP which makes the datagram packets may arrive irrespective of order. UDP is a better solution for time-sensitive applications due to the reason ‘dropping packets is preferable to use delayed packets’. Its stateless nature makes the server to answer smaller queries to huge number of clients.

Working of RSVP

Q. Explain RSVP. How does it work?

Answer: Resource Reservation protocol is used to reserve resources across a network. It is used for requesting a specific Quality of Service (QoS) from the network. This is done by carrying the request (that needs a reservation of the resource) of the host throughout the network. It visits each node in the network. RSVP used two local modules for reservation of resources. Admission control module confirms if there are sufficient available resources while policy module checks for the permission of making a reservation. RSVP offers scalability. On a successful completion of both checks RSVP uses the packet classifier and packet scheduler for the desired Qos requested.

IP Spoofing

Q. What is IP Spoofing and how can it be prevented?

Answer:IP spoofing is a mechanism used by attackers to gain unauthorized access to a system. Here, the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host. This is done by forging the header so it contains a different address and make it appear that the packet was sent by a different machine.
Prevention:-
Packet filtering: - to allow packets with recognized formats to enter the network
Using special routers and firewalls.
Encrypting the session 

What are switches?

Q. What are switches? Explain the concepts of Layer-3 switches.

Answer: It is a device that connects multiple network segments.
A switch analyzes the MAC address and then determines where to send the data.
So a file addressed to a computer reaches only that computer through the use of a switch.
The term ‘switch’ commonly refers to a Network bridge that processes and routes data at the Data link layer (layer 2) of the OSI model.
Switches that additionally process data at the Network Layer are often referred to as Layer 3 switches or Multilayer switches. 

Intranet vs Internet

What's the difference Between an Intranet and the Internet?

Answer: There's one major distinction between an intranet and the Internet: The Internet is an open, public space, while an intranet is designed to be a private space. An intranet may be accessible from the Internet, but as a rule it's protected by a password and accessible only to employees or other authorized users.

From within a company, an intranet server may respond much more quickly than a typical Web site. This is because the public Internet is at the mercy of traffic spikes, server breakdowns and other problems that may slow the network. Within a company, however, users have much more bandwidth and network hardware may be more reliable. This makes it easier to serve high-bandwidth content, such as audio and video, over an intranet.