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Bard is Google’s version of conversational AI similar to ChatGPT which has taken the internet by storm over the past few months. This is due to the nature of human like conversational abilities by these AI systems, more and more people finding it using for a variety of tasks.

When it comes to conversational AI, Google is undisputed given the amount of research and development they have done over the years in this field. Bard is the next addition in their lineup. Although given the timing, Bard is simply recognised as a competitor to ChatGPT rather than a flagship product from Google.

Bard is based on the Language Model for Dialogue Application or LaMDA which was released 2 years also by Google. 

“Bard seeks to combine the breadth of the world’s knowledge with the power, intelligence and creativity of our large language models. It draws on information from the web to provide fresh, high-quality responses” according to the [announcement blog](https://blog.google/technology/ai/bard-google-ai-search-updates/) from Google.

This new product adds to Google’s portfolio of AI models including LaMDA, PaLM, Imagen and MusicLM. All these provides more tools to enhance generational AI and impacting the creativity space. 

As of now, there is no demo version of Bard similar to how [ChatGPT has one.](http://chat.openai.com) However, Google says, these new features will be integrated into Google search soon. 

Also, Google plans to release developer APIs from next month starting with Language API powered by LaMDA and followed by other models soon.

Google introduces Bard which is a conversational AI similar to ChatGPT.

Google introduces Bard, Its answer to ChatGPT


A DNS records is a collection of entries that map a URL to an IP address. These are stored on DNS servers. Although initially, DNS servers only had an URL to IP address mapping, they have evolved and started storing several other information about the URL. All these records have a TTL (time to live). It indicates how long the record is cached in the DNS server.

In order to access a website, a DNS server must store several mandatory records about that website and multiple other optional ones. In this article, let me explain about the most common DNS records.

## The A record

The A record is the most fundamental record in a DNS record. It provides the IPv4 address of a given URL. This is the record that provides the mapping for a URL to an IP address. The browser automatically fetches this record by sending a query to a DNS server.

```jsx
example.com         IN  A       192.168.1.42
```

They are also used for DNSBL list (DNS Blackhole). This is used my mail servers for blocking known mail spammers.

Typically there is only one A record for a single domain name but there can also be many in some cases. This allows to perform load balancing across servers. For example, Route53 in AWS has several multi-region load balancing options based on the health, weight, round-robin, etc. [Refer here](<[https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html)>) for more info.

The default TTL of A record is 14400 seconds or 4 hours.

## The AAAA record

DNS AAAA records match a domain name to an IPv6 address. DNS AAAA records are exactly like DNS A record except that they store a domain's IPv6 address instead of its IPv4 address.

IPv6 are longer form IP address created to address the limitations of IPv4. It is 128 bit whereas IPv4 is 32 bit. This radically increases the number of possible IPv6 addresses.

Except for this change, everything else is same as the A record.

## The CNAME record

The CNAME or Canonical Name is used to notate when a subdomain is an alias of another domain. All CNAME records must point to a domain, never to an IP address.

A lot of websites have domains have subdomains like www.google.com, m.google.com, etc. These domains are pointed to A record(google.com) in a CNAME record. Thus the client can fetch the actual IP address. Once the actual IP address is obtained, the URL is then processed as is, meaning if [shop.amazon.com](http://shop.amazon.com) is the URL, it will have a CNAME to amazon.com and after knowing the actual IP from the A record, the route will still be processed as shop.amazon.com by the server.

A CNAME record can also point to another CNAME record but it is mostly inefficient because it requires two hops to reach the IP address.

Some cloud providers have similar concept but with different name. For example, AWS Route53 has an Alias record which is similar to a CNAME record but a Alias record can point to specific AWS resources like S3 bucket, ELB, API gateway, Cloudfront, etc.

## The MX record

A DNS 'mail exchange' (MX) record directs email to a mail server. It provides information on how to route emails following the SMTP protocol.

```jsx

a.example.com.          IN      MX      mailhost1.example.com
```

The MX records must always point to a domain name.

### Why exactly is a MX record needed?

Similar to how an A record provides information about the IP address, MX record provides information about the mail server. This query is performed by a Mail Transfer Agent(MTA). The MTA then establishes connections to those servers via SMTP protocol.

If you are setting up a custom email domain using a provider like [Google Workspace](https://workspace.google.com/intl/en_in/) for example, then you must configure the MX record and point it to Google’s mail servers.

## The TXT record

The TXT record allows a domain administrator to place text notes.

```jsx
a.example.com.          IN      TXT      hello
```

Most DNS providers place a limit on the number of characters that can go into the TXT record thus it cannot store large values. AWS Route53 has a limit of 255 characters [Refer](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/ResourceRecordTypes.html#TXTFormat)

One of the main purposes these days of a TXT record is domain ownership verification. This comes into play in several places. Examples:

- You registered a domain from a domain registrar and now you wish to host a web application using another hosting service (like [https://vercel.com/](https://vercel.com/dashboard)) in that domain. You have to first verify the ownership via a text record.
- If you are managing SEO for a website(example [https://search.google.com/search-console](https://search.google.com/search-console?utm_source=about-page&resource_id=sc-domain:lyrj.space)), you have to first confirm it is your site using a TXT record.

## The NS record

An NS record (NameServer record) is a DNS record that contains the name of the authoritative name server for that domain. It really is another DNS server that could contain your DNS record. This can also be considered a backup mechanism. For example,

```
a.example.com.          IN      NS      c.example.com
c.example.com.          IN       A      192.168.1.2
```

If you have the above configuration,

If a client requests for a.example.com (or any other subdomains like b.example.com) it will be redirected to 192.168.1.2 to get the actual IP address.

A single domain can have multiple NS records for increased availability. Typically, there is one primary name server and multiple secondary name servers. Updating the primary nameserver will trigger an update of the secondary nameservers as well.

## The SOA record

The SOA record(Start of Authority) record stores important information about a domain such as the email address of the administrator, when the domain was last updated, and how long the server should wait between refreshes. All DNS zones need an SOA record in order to conform to IETF standards

## Follow up

Here is the list of all the other DNS records: [https://en.wikipedia.org/wiki/List_of_DNS_record_types](https://en.wikipedia.org/wiki/List_of_DNS_record_types)

Thanks for reading :-)


Blog explaining various DNS records like A, MX, AAAA, NS, etc.

DNS Records and types


There are several major important networking protocols that have made the internet possible. Learning about them could be overwhelming as a beginner to computer networks. However, knowing these will help you understand how the internet works. Here are the major protocols which I think are the most interesting ones.

## HTTP

HTTP is the very first in the list and the easiest to understand. If you have used the internet, you have used HTTP. Any site you visit works on the basic principles of HTTP. This protocol describes how the browser and a server should transfer files between them. It is stateless i.e The browser fires a request, the server responds and that’s it. The server then never remembers the client again. The most common resources a browser requests are the following: HTML, CSS, JS, Images, Fonts, etc.

HTTP was designed and developed by the genius dude Tim Berners-Lee in 1989 at CERN. Interestingly, he is also the one, who developed the first browser and also the WWW protocol. HTTP/1 was released in 1996 followed by HTTP/1.1 in 1997 and then in 2015, HTTP/2 was released. The latest successor HTTP/3 was released in 2022.

HTTP uses headers which are key value pairs to provide more information about the request and the response. Like this for example:

```jsx
Access-Control-Allow-Origin: *
Age: 2318192
Cache-Control: public, max-age=315360000
Connection: keep-alive
Date: Mon, 18 Jul 2020 16:06:00 GMT
Server: Apache
```

A typical HTTP connection relies on the presence of a reliable transport protocol like the TCP protocol. Making an HTTP call is very simple in most programming languages. Here is an example for Javascript:

```jsx
fetch('http://example.com/movies.json')
  .then((response) => response.json())
  .then((data) => console.log(data))
```

There are also so many other ways to make HTTP calls including CLI tools like cURL and applications like Postman, etc.

## TCP/IP

TCP/IP stands for Transmission Control Protocol and Internet Protocol. TCP/IP is also commonly called as Internet Protocol suite. These are the set of rules that govern the internet. Understanding this suite means you understand the majority of the concepts. These are the layer 4 and layer 3 protocols.

![OSI](https://ik.imagekit.io/v3papq9tf/osi.png?ik-sdk-version=javascript-1.4.3&updatedAt=1675439905713)

The internet operates on the basis of abstraction. A HTTP request does not care about how it reaches the server. A TCP protocol does not care about which computer it talks to. The IP protocol does not care about how the data is sent over the wire. Each of the layer receives a packet, adds additional info to that packet and then sends it. Moreover, these are just software operations written in the Operating system rather than a physical individual layer.

In this regard, TCP/IP defines how a packet is routed, addressed and received. Here is a summary of the operations:

- Once a packet comes from an upper layer using protocols like HTTP, the layer 4 protocol TCP adds information like source port, destination port, sequence number, etc.
- It is then sent to layer 3 which is the IP protocol. It then adds more information to the packet like Source IP address, destination IP address, etc.
- It is then sent to successive layers for transmission over the wire.

### But how is the port and address is determined?

That is the interesting part. Since there are two parties involved in a single request ( client and server ) we need two sets of ports and IP addresses.

Determining the port for a server is easy. It typically depends on the layer 7 protocol. For example, a HTTP server is typically operated in port 80 whereas HTTPS server in port 443. SSH in port 22, etc. These are predetermined and everyone follows these ports.

However, a client is not a server and does not need to operate in a standard port. Therefore for each request, a random port is chosen called the ephemeral port.

### But what is a port in the first place?

A port is a software construct managed by the Operating System. It is used to identify network processes running in a computer. It is a 16 bit integer ranging from 0 to 65535. If you imagine the computer to be a house, ports are the electric sockets through which data flows.

### Now coming to IP addresses

IP address is the network address of a computer or a device. It is typically assigned by the ISP and it changes every time a device reconnects to the network. There are 2 types of IP addresses namely IPv4 and IPv6. IPv4 is 32 bit address whereas IPv6 is 128 bit address.

Thus every server like Google or Apple will have an unique IP address. The data packet is sent to this IP address from the client via the router. The router uses several algorithms to find the shortest path to reach the destination similar to how Google maps find the shortest distance to reach the destination. I will be writing those in detail in future articles.

But if the address of a server is a 32 bit number, how do I reach Google if I type google.com? Good question, that is where DNS comes in.

## DNS

A DNS is a simple protocol that keeps a key-value pair of human readable names and binary IP addresses. Thus when you type google.com, the request is sent to a known DNS server and it returns the IP address of the server. The actual request to Google is then placed. The DNS also helps the server in updating its IP address without affecting the actual domain name.

DNS is known as Domain Name System. It is one of the oldest protocols in existence. The DNS is hugely distributed and could also be described as the phone book of the internet. The following diagram shows the hierarchical nature of the DNS.

![DNS Hierarchy](https://ik.imagekit.io/v3papq9tf/dns-hierarchy.gif?ik-sdk-version=javascript-1.4.3&updatedAt=1675408205855)

But if every computer and device connected to the internet has an IP address, one can imagine that the number of available IP addresses is going to be exhausted quickly. Thus few other concepts like CIDR and NAT were developed. Let’s look at those in a future article.

## ARP

Ok. I obtained the IP address from the DNS server. I know the port. I built the IP packet. But how do I transfer the data over the wire to the server?

This process is governed using some other lower layer protocols mainly the ARP (Address Resolution Protocol) and RARP (Reverse Address Resolution Protocol). To understand both, first we must understand what a MAC address is.

A MAC(Media Access Control) address is the hardware address of a network device (NIC). A MAC address is used by major network devices including Ethernet, Wi-Fi and Bluetooth. A MAC address is 48 bits in length and is usually fixed. It is also called as the burned in address because it never changes.

Now, back to ARP. It is a simple protocol that maps IP address to MAC address. This mapping is managed by the router and added every time a device joins the network. A router acts like the gateway to a network like a home network for example. Multiple devices can be connected to that router. Whenever the router receives a data packet, it must know to which device it must forward the packet to.

Thus it looks at the ARP table. Gets the MAC address for the equivalent IP address and then sends the packet to that device.

The following is an example mapping table:

![ARP Table](https://ik.imagekit.io/v3papq9tf/arp-table.png?ik-sdk-version=javascript-1.4.3&updatedAt=1675408343792)

## But how is the data transmitted over the wire?

There is an entire field of analog and digital communication and contributions from genius people through out history that has made this possible.

Thanks for reading :)


Interesting Networking Protocols - Part 1


This is a list of useful Linux commands. Most of them are basic and they can be used as a reference for developers.

#### files and directories

- ls => list all files
- ls -a => list all files along with hidden ones
- ls -R => list all files and folders recursively
- ls -l => list in long format (shows more info)

- rm \<filename> => deletes a file
- mv \<filename> \<directory path> => moves a file
- mv \<srcFileName> \<destFileName> => renames a file
- cp \<srcFileName> \<destFileName> => copies file
- cp -R \<srcDir> \<destDir> => copies directory

- cat filename => read contents of a file
- cat > filename => writes to file
- touch filename => creates a file, touch is basically used to change file timestamps. Refer [here](https://www.howtoforge.com/tutorial/linux-touch-command/)

- mkdir directory name => makes a directory
- rmdir directory name => removes a directory
- rm -rf directory name => removes a directory recursively along with the files
- mv dirname1 path or dirname => moves or renames directory

- history => list all commands used in the current session
- clear => clears the terminal screen
- pwd => displays the path of the current working directory.

#### file permissions

File permissions will be provided to users, groups and others (in the same order). They can be provided as numbers or letters.

r - read, w - write, x - execute
u - user, g - group, o - other, a - all

0 - no permission
1 - execute
2 - write
3 - execute + write
4 - read
5 - read + execute
6 - read + write
7 - all

- chmod number filename => gives permissions to user,group and others.

Eg: `chmod 777 ex.txt` => gives all permissions to all users, groups and others.

'+' - gives permission
'-' - removes permission
'=' - assigns the given permission

Eg: `chmod u=rw ex.txt` => gives read/write to user
Eg: `chmod a= ex.txt` => removes all permission to all users.

- chgrp group name filename => changes group for a file
- chown user filename => changes owner of a file

#### input/ output directions

- '>' write (stdout)
  Eg: ls -al > filename => writes the output of "ls -al" to the file. If the file already exists, it is **overwritten**.

- '>>' append (stdout)
  Eg: `echo "hi" >> filename` => appends to the file

- '\<' input

File descriptors : 0 - stdin, 1 - stdout, 2 - stderr

##### Error redirection:

This is used to redirect errors to a log file, rather than cluttering the terminal.

Eg: `cat ex.txt 2> error.log` => tries to read the file, if there is any error, it is written to error.log

Here, '2' is the file descriptor for stderr.

#### working with pipes

##### pg, more and less

Show large text in the terminal as scrollable chunks by piping it to the pg, more or less commands.

Eg: `cat large_file.txt | less` => gives a scrollable viewer.

##### grep

Search for a string in the output by piping to grep.

Eg: `ls | grep key` => shows files that have a string "key".

Flags:

- -i => case insensitive
- -c => displays only count
- -n => displays matching line and number
- -v => displays output that didn't match

Eg: `ls | grep -cv key` => displays count to output that didn't match

- grep can also accept regular expressions. Refer [here](https://www.guru99.com/linux-regular-expressions.html)

##### sort

Sort the contents

Eg: `ls | sort` => displays in alphabetic order

Flags:

- -r => reverse
- -n => numerical
- -f => case insensitive

Eg: `ls -l | sort -nk2` => displays content numerically sorted on the second column. (number of hard links in this case)

#### variables

- VARIABLE=value => Set variables in the session.
- $VARIABLE => gets the value of a variable.
- unset VARIABLE => unsets the variable.

#### networking commands

- ping ip => checks the connection
- dig hostname => performs a dns lookup
- ssh -i key username@ip => connects to a remote computer securely. key is the private key file.
- scp -i key.pem source dest => copies a file. remote location should be `host:file`.
- lsof -i protocol:port => list all processes listening on a port.

Eg: `lsof -i tcp:3000` lists all processes listening to port 3000

#### process management

- top => lists all running process
- kill pid => kills a process with the given process id

#### mount device

- lsblk => list all block devices
- mount device id directory => mount a device to a directory

Eg: `mount /dev/sda4 /ex/mnt`

Flags:

- -a => mounts all devices in /etc/fstab
- -l => lists all mounted devices
- -t => type of filesystem (eg: ext4)

- umount device id => unmounts a device

#### manual

- man command name => shows usage of a command

Thanks for reading :)


Networking

DNS Records and types

Interesting Networking Protocols - Part 1

Useful linux commands

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