Network security

Transport generally involves the movement of people or goods forms one place to another via a means of transport. On the other hand, communication is the passing of information or data from one source to another.
Transport usually involves means of transport such as roadways, railways, air travel etc.
Both transport and communication are complementary to each other. But they can also act like substitutes of one another. For example, if you can email the required information to a client, it eliminates the need to travel to go see him.

A subnet mask is a 32 bits address used to distinguish between a network address and a host address in IP address. A subnet mask identifies which part of an IP address is the network address and the host address. They are not shown inside the data packets traversing the Internet. They carry the destination IP address, which a router will match with a subnet.

VLANs reduce the incidence of collisions and decrease the number of network resources wasted by acting as LAN segments. Data packets sent from a workstation in a segment are transferred by a bridge or switch, which will not forward collisions but will send on broadcasts to every network devices.

1) Proxy ARP: It is a system that answers the ARP requests on the behalf of another system. When the request is sent by a system outside of the host’s network, the router acts as a gateway to send the packets outside the networks to their destinations. 

2) Reverse ARP (RARP): It is a convention utilized by the customer framework in LAN to demand its IPv4 address from the gateway-router table. A table is made by the organization manager in the gateway-router that is utilized to discover the MAC address to the relating IP address.

3) Gratuitous ARP: It is a request from the broadcast to get the router’s IP address. It is used when an end system has an IP address but wishes to defend its MAC address from the LAN or to check if the IP address is not used by any other node or system.

4) Inverse ARP: It is used to find the Ip addresses of the systems over LAN from its MAC addresses. It is mostly used in ATM networks, or in frame relays, where level 3 data are acquired from the level 2 data.

A port number is a way to identify a specific process to which an internet or other network message is to be forwarded when it arrives at a server. All network-connected devices come equipped with standardized ports that have an assigned number. These numbers are reserved for certain protocols and their associated function. Hypertext Transfer Protocol (HTTP) messages, for example, always go to port 80 -- one of the most commonly used ports.

1. MAC Address stands for Media Access Control Address. IP Address stands for Internet Protocol Address.
2. MAC Address is a six byte hexadecimal address. IP Address is either a four-byte (IPv4) or a sixteen-byte (IPv6) address.
3. A device attached with MAC Address can retrieve by ARP protocol. A device attached with IP Address can retrieve by RARP protocol.
4. NIC Card’s Manufacturer provides the MAC Address. Internet Service Provider provides IP Address.
5. MAC Address is used to ensure the physical address of a computer. IP Address is the logical address of the computer.
6. MAC Address operates in the data link layer. IP Address operates in the network layer.
7. MAC Address helps in simply identifying the device. IP Address identifies the connection of the device on the network.

Tip 1 : The cross questioning can go intense some time, think before you speak.

Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.

Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the work environment etc.