What is the difference between private and public ip addresses?

Que: What is the difference between private and public IP addresses?

Private IP address of a system is the IP address which is used to communicate within the same network. Using private IP data or information can be sent or received within the same network.

A private IP address is the address space allocated by Inter NIC to allow organizations to create their own private network.

There are three IP blocks (1 class A, 1 class B and 1 class C) reserved for a private use.

The computers, tablets and smartphones sitting behind your home, and the personal computers within an organizations are usually assigned private IP addresses.

Public IP address of a system is the IP address which is used to communicate outside the network. Public IP address is basically assigned by the ISP (Internet Service Provider).

A public IP address is the address that is assigned to a computing device to allow direct access over the Internet.

A web server, email server and any server device directly accessible from the Internet are a candidate for a public IP address.

A public IP address is globally unique, and can only be assigned to a unique device.

Here is the difference between them..!!

PRIVATE IP ADDRESS	PUBLIC IP ADDRESS
Scope is local.	Scope is global.
It is used to communicate within the network.	It is used to communicate outside the network.
Private IP addresses of the systems connected in a network differ in a uniform manner.	Public IP may differ in uniform or non-uniform manner.
It works only in LAN.	It is used to get internet service.
It is controlled by network administrator of the private network	It is controlled by ISP.
It is available in free of cost.	It is not free of cost.
Private IP can be known by entering “ipconfig” on command prompt.	Public IP can be known by searching “what is my ip” on google.
Range: 10.0.0.0 – 10.255.255.255,  172.16.0.0 – 172.31.255.255,  192.168.0.0 – 192.168.255.255	Range: Besides private IP addresses, rest are public.
Example: 192.168.1.10	Example: 17.5.7.8

1 Mark Question Part 2

1. What do you mean by buffer? (બફર એટલે શું ?)

Buffer is used to temporarily store data while it is being moved from one place to another. The purpose of a buffer is to hold data right before it is used. 

2. Write the full name of ARP, DLC and MAC. (એઆરપી, ડીએલસી અને એમએસીનું સંપૂર્ણ નામ લખો.)

MAC: Media Access Control

DLC: Data Link Control 

ARP: Address Resolution Protocol

3. What do you mean by redundant bit? (રીડદંડ બીટ એટલે શું ?)

To detect or correct error some extra bit is added is known as redundant bit. Redundant bits are added by the sender and removed by the receiver.

4. What is the Hamming distance for d(000, 011)? d (000, 011) માટે હેમિંગ અંતર કેટલું છે?

The Hamming distance d(000, 011) is 2 because modulo summation is 

    000 

⊕ 011 

---------

   011          (here in this answer "011" total number of 1 is two).

5. What is the Hamming distance for d(10101, 11110)? (d (10101, 11110) માટે હેમિંગ અંતર કેટલું છે?) 

The Hamming distance d(10101, 11110) is 3 because modulo summation is 

   10101 

⊕ 11110 

------------

   01011     (here is this answer "01011", total number of 1 is three)

6. What do you mean by Hamming Distance? (હમિંગ ડિસ્ટન્સનો તમારો મતલબ શું છે?) 

The Hamming distance between two words is number of differences between corresponding bits. 

Hamming distance is the number of bit positions in which the two bits are different.

In order to calculate the Hamming distance between two strings, and , we perform their XOR operation, (a⊕ b), and then count the total number of 1s in the resultant string.

7. For Data frame 1001101 write the frame with even parity. (ડેટા ફ્રેમ 1001101 માટે ઇવન પેરીટી ફ્રેમ લખો.)

( Procedure:  In the case of even parity, for a given set of bits, the number of 1’s are counted. If that count is odd, the parity bit value is set to 1, making the total count of occurrences of 1’s an even number. If the total number of 1’s in a given set of bits is already even, the parity bit’s value is 0. )

here data frame : "1001101" 

count the number of "1" = 4  ( which is already even, so add value "0" parity) 

Answer:  Even parity Frame is : "10011010"

8. For Data frame 1001101 write the frame with odd parity. (ડેટા ફ્રેમ 1001101 માટે ઓડ પેરીટી ફ્રેમ લખો.)

( Procedure: In the case of odd parity, for a given set of bits, the number of 1’s are counted. If that count is even, the parity bit value is set to 1, making the total count of occurrences of 1’s an odd number. If the total number of 1’s in a given set of bits is already odd, the parity bit’s value is 0. )

here data frame : "1001101" 

count the number of "1" = 4  ( which is even, so add value "1" parity) 

Answer:  Even parity Frame is : "10011011"

9. write the binary pattern for the polynomial   x⁷ + x⁶ + x⁴ + x³ + x + 1.

(બહુપદી x⁷ + x⁶ + x⁴ + x³ + x + 1.. માટે બાયનરી પેટર્ન લખો.)

The corresponding binary pattern is obtained as-

Thus, for the given Polynomial the corresponding binary pattern is 11011011.

1 Mark Question Part 1

1. Give definition of Protocol.  (પ્રોટોકોલની વ્યાખ્યા આપો.)

A protocol is a standard set of rules that allow electronic devices to communicate with each other. 

These rules include what type of data may be transmitted, what commands are used to send and receive data, and how data transfers are confirmed.

2. What are the types of physical topology? (ફિઝિકલ ટોપોલોજીના કયા પ્રકારો છે?)

Types of topology are Bus Topology, Ring Topology, Star Topology, Tree Topology, Mesh Topology, Hybrid Topology.

3. Give the definition of Physical Topology. (ફિઝિકલ ટોપોલોજીની વ્યાખ્યા આપો.)

The physical topology of the network refers to the configuration of cables,computers and other peripherals. 

It is the way you physically lay out the network, like a map. 

4. What is full-form of IEEE and ISO? ( IEEE અને ISO નું ફુલફોર્મ શું છે?)

IEEE = Institute of Electrical and Electronics Engineers

ISO = International Organization for Standardization

5. Write the name of Application Layer Protocols. (એપ્લિકેશન લેયર પ્રોટોકોલનું નામ લખો.)

Application Layer Protocol: TELNET, FTP, TFTP, SMTP, SNMP

6. Write the names of transport layer protocol. (ટ્રાન્સપોર્ટ લેયર ના પ્રોટોકોલનું નામ લખો.)

Transport Layer Protocol:  TCP, UDP 

7. Write the names of Network Layer protocol. (નેટવર્ક લેયર પ્રોટોકોલનું નામ લખો.)

Network Layer protocol:  ARP, IP, RARP, ICMP, IGMP 

8. Give one example of Simplex, Half Duplex and Full Duplex Communication system. (સિપ્લેક્સ, હાફ ડુપ્લેક્સ અને ફુલ ડુપ્લેક્સ કમ્યુનિકેશન સિસ્ટમ નું એક ઉદાહરણ આપો.)

Example of simplex mode are:Keyboard and monitor.
Example of half duplex mode is: Walkie-Talkies.
Example of half duplex mode is:Telephone.

9. Write the name of 7 layers of OSI Model. (OSI મોડેલના 7 સ્તરોનું નામ લખો.)

Layer Name :
Layer 7 - Application
Layer 6 - Presentation
Layer 5 - Session
Layer 4 - Transport
Layer 3 - Network
Layer 2 - Data Link
Layer 1 - Physical

10. Which layer will do the task of flow and error control? (પ્રવાહ અને ભૂલ નિયંત્રણનું કાર્ય કયા સ્તર કરશે?)

Data Link Layer will do the task of flow and error control. 

Transport Layer can also do the task of error control. 

Explain Simplest Protocol and Stop and Wait Protocol for Noiseless Channel.

Question: Explain Simplest Protocol and Stop and Wait Protocol for Noiseless Channel. 

Answer 

Noiseless Channel

An ideal channel in which no frames are lost, duplicated or corrupted is regarded as Noiseless Channel.

Simplest Protocol

• In simplest protocol, there is no flow control and error control mechanism. It is a unidirectional protocol in which data frames travel in only one direction (from sender to receiver).
• Also, the receiver can immediately handle any received frame with a processing time that is small enough to be negligible.
• The protocol consists of two distinct procedures :a sender and receiver. The  sender runs in the data link layer of the source machine and the receiver runs in the data link layer of the destination machine. No sequence number or acknowledgements are used here.

Stop and Wait Protocol

• The simplest retransmission protocol is stop-and-wait.
• Transmitter (Station A) sends a frame over the communication line and then waits for a positive or negative acknowledgement from the receiver (station B).
• If no error occurs in the transmission, station B sends a positive acknowledgement (ACK) to station A.
• Now, the transmitter starts to send the next frame. If frame is received at station B with errors, then a negative acknowledgement(NAK) is sent to station A. In this case, station 'A' must retransmit the old packet in a new frame.
• There is also a possibility that the information frames or ACKs may get lost.
• Then, the sender is equipped with a timer. If no recognizable acknowledgement is received when the timer expires at the end of time out interval,  the same frame is sent again.
• The sender which sends one frame and then waits for an acknowledgement before the process is known as stop and wait.

Differences between IPv4 and IPv6

Que: Differences between IPv4 and IPv6

IPv4 and IPv6 are internet protocol version 4 and internet protocol version 6, IP version 6 is the new version of Internet Protocol, which is way better than IP version 4 in terms of complexity and efficiency.

Sr No	IPv4	IPv6
1	32-bit address length	128-bit address length
2	Address representation of IPv4 in decimal	Address Representation of IPv6 is in hexadecimal
3	IPv4 has header of 20-60 bytes.	IPv6 has header of 40 bytes fixed
4	In IPv4 Encryption and Authentication facility not provided	In IPv4 Encryption and Authentication facility not provided
5	It has broadcast Message Transmission Scheme	It has broadcast Message Transmission Scheme
6	It supports DHCP or Manual Configuration	It supports autoconfiguration
7	4.3 billion addresses available	7.91028addresses available
8	Example: Numeric dot-decimal notation 192.168.5.18	Example: Alphanumeric hexadecimal notation 50b2:6400:0000:0000:6c3a:b17d:0000:10a9
9	Less security	High security (inbuilt)
10	In IPv4 end to end connection integrity is Unachievable	In IPv6 end to end connection integrity is Achievable

Differences between Pure and Slotted Aloha

Que: Differences between Pure and Slotted Aloha

Aloha is the type of Random access protocol, It have two types one is Pure Aloha and another is Slotted Aloha.

In Pure Aloha, Stations transmit whenever data is available at arbitrary times and Colliding frames are destroyed. While In Slotted aloha, A station is required to wait for the beginning of the next slot to transmit. vulnerable period is halved as opposed to pure Aloha.

Sr No	PURE ALOHA	SLOTTED ALOHA
1	In this aloha, any station can transmit the data at any time.	In this, any station can transmit the data at the beginning of any time slot.
2	In this, The time is continuous and not globally synchronized.	In this, The time is discrete and globally synchronized.
3	Vulnerable time for pure aloha = 2 x Tt	Vulnerable time for Slotted aloha = Tt
4	In Pure Aloha, Probability of successful transmission of data packet = G x e-2G	In Slotted Aloha, Probability of successful transmission of data packet = G x e-G
5	In pure aloha, Maximum efficiency = 18.4%	In slotted aloha, Maximum efficiency = 36.8%
6	Pure aloha doesn’t reduces the number of collisions to half.	Slotted aloha reduces the number of collisions to half and doubles the efficiency of pure aloha.

Differentiate Connection-less and Connection-Oriented Protocol.

Question: Differentiate Connection-less and Connection-Oriented Protocol. 

Answer

Connection-less Protocol

In a connectionless protocol, frames are sent from one node to the next without any relationship between the frames; each frame is independent. Note that the term connectionless here does not mean that there is no physical connection (transmission medium) between the nodes; it means that there is no connection between frames. The frames are not numbered and there is no sense of ordering. Most of the data-link protocols for LANs are connectionless protocols.

Connection-Oriented Protocol

In a connection-oriented protocol, a logical connection should first be established between the two nodes (setup phase). After all frames that are somehow related to each other are transmitted (transfer phase), the logical connection is terminated (teardown phase). In this type of communication, the frames are numbered and sent in order. If they are not received in order, the receiver needs to wait until all frames belonging to the same set are received and then deliver them in order to the network layer. Connection Oriented protocols are rare in wired LANs, but we can see them in some point-to-point protocols, some wireless LANs, and some WANs.

OR

What is DNS ? How does it work ?

Question: What is DNS ? How does it work ?

Answer 

DNS, or the Domain Name System, translates human readable domain names (for example, www.amazon.com) to machine readable IP addresses (for example, 192.0.2.44).

There are 4 DNS servers involved in loading a webpage: 

DNS recursor/ DNS resolver: It is basically provided by the ISP (like Jio, Airtel, Idea). The DNS recursor is a server designed to receive queries from client machines through applications such as web browsers. Typically the recursor is then responsible for making additional requests in order to satisfy the client’s DNS query.

Root Name Server: It is operated by 12 organizations. There are 13 sets of root name servers. A name server is a computer that answers questions about domain names, such as IP addresses. These 13 servers act as a kind of telephone switchboard for DNS. They don’t know the answer, but they can direct DNS queries to someone that knows where to find it.

TLD Name Server: The top level domain server (TLD) is the next step in the search for a specific IP address, and it hosts the last portion of a host name (In example.com, the TLD server is “com”). Each TLD, such as those for .com, .org, and .us, has its own set of name servers, which act like a receptionist for each TLD. These servers don’t have the information we need, but they can refer us directly to the servers that do have the information.

Authoritative Name Servers: The authoritative name server is the last stop in the name server query. These authoritative name servers are responsible for knowing all the information about a specific domain, which is stored in DNS records. The authoritative name server has access to the requested record and it will return the IP address for the requested host name back to the DNS Recursor that made the initial request.

A user opens a web browser, enters www.example.com in the address bar, and presses Enter.

The request for www.example.com is routed to a DNS resolver, which is typically managed by the user's Internet service provider (ISP), such as a cable Internet provider, a DSL broadband provider, or a corporate network.

The DNS resolver for the ISP forwards the request for www.example.com to a DNS root name server.
The DNS resolver for the ISP forwards the request for www.example.com again, this time to one of the TLD name servers for .com domains. The name server for .com domains responds to the request with the names of the four Amazon Route 53 name servers that are associated with the example.com domain.
The DNS resolver for the ISP chooses an Amazon Route 53 name server and forwards the request for www.example.com to that name server.
The Amazon Route 53 name server looks in the example.com hosted zone for the www.example.com record, gets the associated value, such as the IP address for a web server, 192.0.2.44, and returns the IP address to the DNS resolver.

The DNS resolver for the ISP finally has the IP address that the user needs. The resolver returns that value to the web browser. The DNS resolver also caches (stores) the IP address for example.com for an amount of time that you specify so that it can respond more quickly the next time someone browses to example.com. For more information, see time to live (TTL).

The web browser sends a request for www.example.com to the IP address that it got from the DNS resolver. This is where your content is, for example, a web server running on an Amazon EC2 instance or an Amazon S3 bucket that's configured as a website endpoint.
The web server or other resource at 192.0.2.44 returns the web page for www.example.com to the web browser, and the web browser displays the page.