Subnetting - two Marks

1. What is virtual circuit? 

In computer networks, a virtual circuit (VC), synonymous with virtual connection and communication service that is delivered by means of packet mode communication. After a connection or virtual circuit is established between two nodes or application processes, a bit stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames. Virtual circuit communication resembles circuit switching, since both are connection oriented.

2. What is a datagram?

 A datagram is a basic transfer unit associated with a packet-switched network in which the delivery, arrival time, and order of arrival are not guaranteed by the network service. A datagram has the following characteristics: Data is transmitted from source to destination without guarantee of delivery Data is frequently divided into smaller pieces and transmitted without a defined route or guaranteed order of delivery

3. What is the use of TTL packet in IP header? 

The time-to-live (TTL) is the number of hops that a packet is permitted to travel before being discarded by a router. Originally TTL was set to a specific number of seconds that the packet would be allowed to live. The TTL is set in an eight binary digit field in the packet header by the sending host and is used to prevent packets from endlessly circulating on the Internet or other network. When forwarding an IP packet, routers are required to decrease the TTL by at least one. If a packet's TTL field reached zero, the router detecting it discards the packet and sends an ICMP (Internet control message protocol) message back to the originating host.

4. What is DHCP? 

DHCP - Dynamic Host Configuration Protocol DHCP is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of IP addresses configured for a given network so that it can communicate on that network using the Internet Protocol (IP). The protocol is implemented in a client-server model, in which DHCP clients request configuration data, such as an IP address, a default route, and one or more DNS server addresses from a DHCP server.

5. What are salient features of IPv6?

Major Features of IPv6: New Packet Format and Header Expanded Addressing (Large address space) Address Autoconfiguration and Neighbor Discovery Header Format Simplification Improved Support for IP Header Options Multicasting Built in Integrated Internet Protocol Security (IPSec)

6. Write the importance of routing table. 

A routing table contains the information necessary to forward a packet along the best path toward its destination. Each packet contains information about its origin and destination. When a packet is received, a network device examines the packet and matches it to the routing table entry providing the best match for its destination. The table then provides the device with instructions for sending the packet to the next hop on its route across the network. A basic routing table includes the following information: Destination: The IP address of the packet's final destination Next hop: The IP address to which the packet is forwarded Interface: The outgoing network interface the device should use when forwarding the packet to the next hop or final destination Metric: Assigns a cost to each available route so that the most cost-effective path can be chosen Routes: Includes directly-attached subnets, indirect subnets that are not attached to the device but can be accessed through one or more hops, and default routes to use for certain types of traffic or when information is lacking.

7. Define subnetting. 

Subnetting is the strategy used to partition a single physical network into more than one smaller logical sub-networks (subnets). An IP address includes a network segment and a host segment. Subnets are designed by accepting bits from the IP address's host part and using these bits to assign a number of smaller sub-networks inside the original network. Subnetting allows an organization to add sub-networks without the need to acquire a new network number via the Internet service provider (ISP). Subnetting helps to reduce the network traffic and conceals network complexity. Subnetting is essential when a singlenetwork number has to be allocated over numerous segments of a local area network (LAN). Subnets were initially designed for solving the shortage of IP addresses over the Internet.

8. What is multicasting? 

In computer networking, multicastinf is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source. Multicast is most commonly implemented in IP multicast, which is often employed in Internet Protocol (IP) applications of streaming media and Internet television. In IP multicast the implementation of the multicast concept occurs at the IP routing level, where routers create optimal distribution paths for datagrams sent to a multicast destination address.

9. Define CIDR.

Short for Classless Inter-Domain Routing, an IP addressing scheme that replaces the older system based on classes A, B, and C. With CIDR, a single IP address can be used to designate many unique IP addresses. A CIDR IP address looks like a normal IP address except that it ends with a slash followed by a number, called the IP network prefix. For example: 192.168.15.1/24 The IP network prefix specifies how many addresses are covered by the CIDR address, with lower numbers covering more addresses. An IP network prefix of /12, for example, can be used to address 1,048,576 former Class C addresses. CIDR addresses reduce the size of routing tables and make more IP addresses available within organizations.

10. What is RIP?

The Routing Information Protocol (RIP) is one of the oldest distance-vector routing protocol, which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. RIP is classified by the Internet Engineering Task Force (IETF) as one of several internal gateway protocols (Interior Gateway Protocol).