<commit_before>DNS
===
The Domain Name System (DNS) is a central part of the Internet, providing a way to match names (a website youre seeking) to numbers (the address for the website). Anything connected to the Internet - laptops, tablets, mobile phones, websites - has an Internet Protocol (IP) address made up of numbers. Your favorite website might have an IP address like 172.16.17.32, but this is obviously not easy to remember. However a domain name such as bestdomainnameever.com is something people can recognize and remember. DNS syncs up domain names with IP addresses enabling humans to use memorable domain names while computers on the Internet can use IP addresses.

Lets explore what keeps billions of Internet users and 284 million domain names* connectingand how Verisign helps to make it happen.

####Introduction Video
<a href="http://www.youtube.com/watch?feature=player_embedded&v=GlZC4Jwf3xQ
" target="_blank"><img src="http://img.youtube.com/vi/GlZC4Jwf3xQ/0.jpg" 
alt="http://img.youtube.com/vi/GlZC4Jwf3xQ/15.jpg" width="540" height="380" border="10" /></a>

####The Query
The process begins when you ask your computer to resolve a hostname, such as visiting http://dyn.com. The first place your computer looks is its local DNS cache, which stores information that your computer has recently retrieved.
If your computer doesnt already know the answer, it needs to perform a DNS query to find out.

DNS client will make a query to the root server. The server gives another root server information which has .com domain

			```DNS CLIENT ```  -->  ```ROOT SERVER``` 

The query look like the following one,

	for example .com
	```example.com 	IN 	A```
	```example.com``` - the domain to look up
	```IN``` - The DNS class (Internet)
	```A``` - The record type (address) -  We are looking for the address of the top level domain server
	
			 ```DNS CLIENT```  <--  ```ROOT SERVER```
	**Authority Section:**
		com.	172800	IN	NS	m.gltd-servers.com
		com.	172800	IN	NS	l.gltd-servers.com
		com.	172800	IN	NS	k.gltd-servers.com
		com.	172800	IN	NS	j.gltd-servers.com
	
	```172800``` - Time to live (How long the information is valid)
	```IN``` - DNS class(Internet)
	```NS``` - Name server(Authoritative server for .com domain)
	```m.gltd-servers.com``` - Domain Name for each name servers
	
	But with domain name alone we cant reach this DNS servers because we need IP address. So the IP address info is available in the additional section.
	
	**Additional Section:**
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
	

####Ask the recursive DNS servers
If the information is not stored locally, your computer queries (contacts) your ISPs recursive DNS servers. These specialized computers perform the legwork of a DNS query on your behalf. Recursive servers have their own caches, so the process usually ends here and the information is returned to the user.

####Ask the root nameservers
If the recursive servers dont have the answer, they query the root nameservers. A nameserver is a computer that answers questions about domain names, such as IP addresses. The thirteen root nameservers act as a kind of telephone switchboard for DNS. They dont know the answer, but they can direct our query to someone that knows where to find it.

####Ask the TLD nameservers
The root nameservers will look at the first part of our request, reading from right to left  www.dyn.com  and direct our query to the Top-Level Domain (TLD) nameservers for .com. Each TLD, such as .com, .org, and .us, have their own set of nameservers, which act like a receptionist for each TLD. These servers dont have the information we need, but they can refer us directly to the servers that do have the information.
<commit_msg>Updated dns<commit_after>DNS
===
The Domain Name System (DNS) is a central part of the Internet, providing a way to match names (a website youre seeking) to numbers (the address for the website). Anything connected to the Internet - laptops, tablets, mobile phones, websites - has an Internet Protocol (IP) address made up of numbers. Your favorite website might have an IP address like 172.16.17.32, but this is obviously not easy to remember. However a domain name such as bestdomainnameever.com is something people can recognize and remember. DNS syncs up domain names with IP addresses enabling humans to use memorable domain names while computers on the Internet can use IP addresses.

Lets explore what keeps billions of Internet users and 284 million domain names* connectingand how Verisign helps to make it happen.

####Introduction Video
<a href="http://www.youtube.com/watch?feature=player_embedded&v=GlZC4Jwf3xQ
" target="_blank"><img src="http://img.youtube.com/vi/GlZC4Jwf3xQ/0.jpg" 
alt="http://img.youtube.com/vi/GlZC4Jwf3xQ/15.jpg" width="540" height="380" border="10" /></a>

####The Query
The process begins when you ask your computer to resolve a hostname, such as visiting http://dyn.com. The first place your computer looks is its local DNS cache, which stores information that your computer has recently retrieved.
If your computer doesnt already know the answer, it needs to perform a DNS query to find out.

DNS client will make a query to the root server. The server gives another root server information which has .com domain

```DNS CLIENT ```  -->  ```ROOT SERVER``` 

The query look like the following one,

	for example .com
	```example.com 	IN 	A```
	```example.com``` - the domain to look up
	```IN``` - The DNS class (Internet)
	```A``` - The record type (address) -  We are looking for the address of the top level domain server
	
```DNS CLIENT```  <--  ```ROOT SERVER```
	**Authority Section:**
		com.	172800	IN	NS	m.gltd-servers.com
		com.	172800	IN	NS	l.gltd-servers.com
		com.	172800	IN	NS	k.gltd-servers.com
		com.	172800	IN	NS	j.gltd-servers.com
	
	```172800``` - Time to live (How long the information is valid)
	```IN``` - DNS class(Internet)
	```NS``` - Name server(Authoritative server for .com domain)
	```m.gltd-servers.com``` - Domain Name for each name servers
	
	But with domain name alone we cant reach this DNS servers because we need IP address. So the IP address info is available in the additional section.
	
	**Additional Section:**
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
		m.gltd-servers.com	172800	IN	A	172.16.17.32
	

####Ask the recursive DNS servers
If the information is not stored locally, your computer queries (contacts) your ISPs recursive DNS servers. These specialized computers perform the legwork of a DNS query on your behalf. Recursive servers have their own caches, so the process usually ends here and the information is returned to the user.

####Ask the root nameservers
If the recursive servers dont have the answer, they query the root nameservers. A nameserver is a computer that answers questions about domain names, such as IP addresses. The thirteen root nameservers act as a kind of telephone switchboard for DNS. They dont know the answer, but they can direct our query to someone that knows where to find it.

####Ask the TLD nameservers
The root nameservers will look at the first part of our request, reading from right to left  www.dyn.com  and direct our query to the Top-Level Domain (TLD) nameservers for .com. Each TLD, such as .com, .org, and .us, have their own set of nameservers, which act like a receptionist for each TLD. These servers dont have the information we need, but they can refer us directly to the servers that do have the information.

{'fraction_non_alphanumeric': 0.08055086397297648, 'fraction_numerical': 0.03092113810575549, 'mean_word_length': 4.081188118811881, 'pattern_counts': {'":': 0, '<': 11, '<?xml version=': 0, '>': 11, 'https://': 0, 'lorem ipsum': 0, 'www.': 4, 'xml': 0}, 'pii_count': 10, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '5890765', 'n_tokens_mistral': 2434, 'n_tokens_neox': 2157, 'n_words': 1117}