Question

1. What is OSPF? What is the latest version? In addition, how does it work?

2. What is BGP? What is the latest version? How does it work?

3. What is SDN? Why SDN has gained in importance during last few years? How is it different from

   traditional implementation?

4. What are the services offered by the Data Link layer?

5. Why is Ethernet still dominant in wired LAN networks? And has even spread to WAN in certain

   cases.

6. What are the latest standards {1 now and 1 upcoming} in wireless LAN? How did they evolve

   from the original 1997, IEEE ratified the original 802.11 standard?

7. What is the role of cryptography in network security? Compare symmetric and asymmetric

   encryption.

8. What is the latest Wireless encryption standard? How does it compare to original WEP?

9. What types of multi-media services are offered through the Internet? What kind of bandwidth

   requirements are necessary for their implementation?

10. What is Voice-over-IP? How are its hurdles mitigated?

Thank you!!!

Answer 1

* What is the role of cryptography in network security? Compare symmetric and asymmetric encryption.
Answer: Cryptography basically provides security in networks. It provides encryption and decryption services to secure data at rest and in transit. Encryption lets critical, financial, confidential, and sensitive information to pass through network securely and safely. Also, another service or function it offers is the authentication mechanisms. Cryptography is mainly and widely used in financial sectors or industries such as Banks and other financial institutions to transfer, transact payments, etc.

Symmetric key encryption: It uses a single key required to be shared among the people who need to send and receive the messages amongst themselves.
* It does not need many CPU cycles for processing. Hence, it is faster.
* It uses a secret key, same used both, for encryption and decryption.
* This mechanism is older.

Asymmetric key encryption: It uses a pair (key-pair) of public and private keys to encrypt and decrypt messages respectively when communicating.
* It needs many CPU cycles for processing. Hence, it is slower.
* It uses public and a private key, for encryption and decryption respectively.
* This mechanism is newer.

* What is the latest Wireless encryption standard? How does it compare to the original WEP?
Answer:

WPA2-PSK (AES) is the acronym for Wi-Fi Protected Access 2 Pre-shared Shared Key Advanced Encryption Standard option chosen while setting up wireless networks, especially Wi-Fi networks and it is the most secure option. It uses the current or the latest standard which is WPA2. WPA2 uses encryption devices that encrypt the network with a 256-bit key and uses the latest AES encryption protocol.

WEP 64 and WEP 128, both are risky, dangerous, and are vulnerable to cyber attacks and hacking. WEP is the acronym for Wired Equivalent Privacy. It is a notoriously weak security standard. It is a weakly encrypted system. The WEP key can be obtained from a remote client thus compromising the system.

* What are the services offered by the Data Link layer?
Answer: It offers the below services:
* Encapsulation service, to encapsulate the network layer data packets into frames.
* Frame synchronization.
* Flow Control: This prevents from controlling the flow of frames from a fast sender overwhelming slower receiver.
* Error control: Sender checksums the frame and transmits data with the checksum to the receiver, where the receiver re-computes the checksum and compares it with the received value.
* Multiple access protocols for collisions detection and avoidance.
* MAC (Media Access Control) addressing.
* LAN switching including MAC filtering, Spanning Tree Protocol (STP), and Shortest Path Bridging (SPB).
* Data packet queuing.
* Quality of Service (QoS) control.
* Virtual LANs (VLAN).
* Store-and-forward switching.

* What is BGP? What is the latest version? How does it work?
Answer: BGP is the acronym for Border Gateway Protocol. It is the path-vector routing protocol making the Internet work, providing routing information for autonomous systems on the Internet through its AS-Path attribute. It is a layer 4 (Transport) protocol. It is basically used to route traffic across the Internet.

The current or the latest version is BGP version 4, based on RFC4271.

To use this protocol, one has to manually set up the peers forming a TCP connection and start initiating BGP for exchanging routing information amongst the routers, and other networking devices and components on the network, or the Internet. BGP, for transport protocol, uses TCP on port 179. In a basic setup, two BGP routers been setup establish a TCP connection between them. These are peer routers, as any two routers establishing a TCP connection to exchange BGP routing information are called peers. Every peer's address should be specified manually. The protocol does not discover its peers dynamically. BGP learns routes from different peers. Also, it adds its own routes. It further decides what path toward the desired destination is the best one. Finally, for each known destination, it sends this single best route to its peers.

What is Voice-over-IP? How are its hurdles mitigated?
Answer: Voice-over-Internet Protocol is also called IP telephony. The acronym is VoIP. It is a technology to transmit voice communications data and multimedia content over IP networks, such as the Internet. It is a technology used on the Internet to make voice or audio calls through a broadband Internet connection rather using the conventional analog (phone) line.

The hurdles in VoIP are mitigated using the below methods and technologies:
* Encryption implementation for securing the communications.
* It gets rid of the old Public Switched Telephone Network (PSTN) systems by converting audio signals to digital data, and that data is then sent over the Internet rather using circuits to connect audio signals over analog lines in PSTN systems.
* It is hassle-free technology, as you do not need two different networks, one for data and another for your audio. VoIP uses the same Internet infrastructure you use it for web browsing and e-mail to send voice calls.