DNS Beyond Basics: 6 Records That Fix 91% Of Dns Issues in Production!

Only one thing which is the most

important thing when it comes to running

anything over the internet is the DNS.

And I'm sure that if you are anywhere

related to IT or tech then you already

know what is DNS at a junior level or at

a basic level. But what separates a

junior level information versus a senior

like how interviews go through when you

are a senior when people expect you to

understand the design part of it or

architecture part of DNS then you are

not talking simply about resolution. So

basically whenever anyone ask you okay

what is a domain name server you simply

have the definition marked up that it is

useful for name resolution. So what is

name resolution? Name resolution is

simply you getting a name of a website

and then you're typing it. For example

www.google.com

because it is more human readable. You

do it and then it routes you to 8.8.8.8

which is the IP address of this name to

IP resolution is done by your DNS. If

you take a analogy for it then you know

if someone has to send anything on your

house address then they will you know

simply write house number 1 2 3 lane six

post code something something and it

will directly understand that it is

going for Mr. Kumar that is Kumar's

house. Okay. So just a gist of what is

DNS. We have a basic video on DNS where

we talk about it at length but just to

understand it. But I think where we move

from junior to senior is when we move

from resolutions to records. And today

we'll talk about six such records. Okay.

These six records will separate you from

having a basic information of DNS versus

someone who has actually worked on DNS

or who has more experience going for

some senior level interviews. and also

almost all the outages which you see if

DNS has a role to play, you will have a

look into these six records. It's a

starting point. It is next level from

DNS basics and I think this will be

really helpful for you. So watch till

the end and I'm pretty sure that you

will have some useful information at the

end of this video. By the way, if you're

new to this channel, hi, I'm Anuli and

I'm working in IT from last two decades

and this channel has been running for 6

years now and the idea is simple. I want

you guys to come on a journey with me

and transform your knowledge. It could

be technical knowledge, it could be

domain knowledge, it could be business

knowledge. Whatever it is, the thing is

the way it is changing right now, you

need multiple skills. You cannot fixate

yourself with one particular domain. So

my thing is whatever I have learned in

IT I want to pour down that knowledge

onto you and I want you if you are at 8

years 10 years 12 years experience I

want you to take that next step and move

into a consultant role an architect role

a senior engineer role that is where I

am heading and I hope by subscribing to

this channel you can also join me on

this journey and make it worth doing

okay so do consider subscribing and do

like it if you find any value so let's

get started so the first and the most

basic or I would say the most important

important record in any DNS setting is

your A record. A record is nothing

simple. It does what DNS stands for at a

high level which is it has the name of

the domain. So we'll take

www.example.com

throughout uh this video and we will see

how different uh records map to this

particular domain. So www.example.com

is our domain and the A record simply

means we'll map the exact IP address,

the exact IPv4 address which is mapped

to this particular domain. Okay. And

what is TTL? TTL is simply time to live.

So how long this going to stay in this

table and 3600 means it is for 1 hour.

So it is 3600 seconds. Simply if you

face uh any issue while migration of for

example your database server or your

application server. It could be that

your A record is still pointing to the

old IP address. You have not updated

your A record or maybe your TTL has not

yet expired. So it might be a

possibility that uh for the next 1 hour

or 2 hour the record is still active

while users are trying to hit the domain

and it should route to the new IP

address it is still pointing to the old

one. So you have to also think on those

lines when someone throws a scenario-

based question to you, you have to think

about okay which particular record might

be into play in this particular

scenario. And a good practice is

whenever you are doing any such

migration, you lower this TTL value to

maybe 60 seconds or maybe few minutes

rather than hours so that you can do

your testing. So that is your a record.

Now I have written this along along with

that because it is very close brother of

a record which is a a a record. So this

is nothing but your IPv6 record. As you

know we have a video on IPv4 versus

IPv6. You can watch that. But IPv6

simply means that now because we have

limited numbers of IPv4 address, we are

moving to IPv6 slowly and gradually. And

that's why your DNS it is an optional

record guys because it can have some

downsides as well. Let me explain. So

everything remains the same. It's just

that it is a IPv6 address. But the thing

is now if you are working an environment

or you are working for a customer who's

using dual stack IP which is like you're

using IPv4 but at the same time you're

using IPv6 and if the priority is IPv6

then it might be that when you send any

request to this particular domain it

first goes to IPv6 and then it

prioritize IPv4. Okay. But at the same

time you have to be careful because

sometimes what happens is that in uh in

certain environment you don't have this

record IPv6 but you have a dual IP

environment a dual stack IP environment

then what's happening is it is first

going and searching for IPv6 in your DNS

it is not finding it and then it is

falling back to IPv4. So now that could

add latency or the performance slowness

into your request. So you have to be

careful like if you want you can have it

but if you want you can completely omit

this and you can simply work with this

almost everywhere you will rarely find

this as of now but as we will go along

this will become more and more prominent

into your DNS record. So a record and a

aaa record is IPv4 and IPv6 entry. So

the third record on our list is CNAME

record which is also called as canonical

name. It is nothing but a forwarding

address. you are forwarding requests

from one of your domains to another

domain and generally it is used in cloud

very heavily because you are using

content delivery networks you're using

load balancers and basically it is

routing it is basically saying I don't

know where to go but I know that this

guy might know it's like if you enter a

very big IT park and you go into a very

big co-working space and you ask for

okay where this XYZ startup is at the

ground floor of the reception and if

that receptionist say if you want to go

for a then go to the receptionist at

level three or floor three. So what they

are saying they're just routing it to

the receptionist at level three or floor

three. So this is what is forwarding

very much used in DNS setups and uh this

is what forwarding is all about. So

sometimes what happens is that if your

CNAME records are messed up then it

might happen that you know your load

balancers your backend load balancers

have been misconfigured or you get the

errors like domain not found. you need

to check if there is any discrepancy

within your DNS table and DNS records

and if all the load balancers have been

correctly mapped. So a very good record,

a very important record and very good

thing to know during your interviews.

The fourth in our uh list is the NS

record. NS stands for name server. So

basically as you know in DNS you have

this wide world of different domains at

different levels. So you first of all

have a root domain. Okay. So when we

type www.google google.com there is

actually a dot at the end you can check

it uh we don't put it but it is called

as your root domain now that root domain

sends the request to your tld which is

called as tople domain and then tople

domain will send it to the actual name

server or we can also say authorization

server which holds the IP address of

that particular domain example.com it

could be for example AWS route 53 or

godaddy okay so these records are held

at these levels and then the TTL is

quite high because you rare ly changed

the records the NS records. It's only

when you are migrating for example your

domain from GoDaddy to AWS then that is

the time when you will have to wait for

certain time to get this updated.

Generally if you see if you migrate your

domain from one domain provider to

another then you have to wait for at

least 48 hours. So that is what is the

name server records. It actually tells

where actually the root domain and the

top level domain has to go in order to

find the IP. The next one in our list is

very different from whatever we have

discussed because this particular record

does not route a request to some other

destination. This record is like a

constitution. It tells whatever this

whole DNS zone is all about. It sets

that and that's why it is called as part

of authority because it sets out

whatever information is needed to

understand what this whole DNS zone is

all about. So it will have data like

your name server record what is your

email admin at the rate example.com the

serial number manages the version of

this whole DNS setup and then refresh

retry these kind of settings are there

that how frequently you have to refresh

this whole table so all that is

commanded by your record it also has

this feature of negative TTL like for

example if someone searches for

nope.example.com example.com. So

negative TTL means that okay if it is

not there currently present then for how

long it won't be present because it

might happen that you are actually right

now building no.example.com. So that

negative TTL would mean that internet

would treat that this does not exist

only for next 24 hours but after that it

has to again come and check because we

might be building this right now. Okay.

So that is called as managing the

negative TTL. So yeah that's uh our

start of authority record. So the last

on our list is the tax record and the

tax record is primarily used for setting

up the ownership like showing to the

world that who owns this particular

domain and that is where you know for

example if you're migrating you your

domain and adding Google workspaces then

you will add a line which I maybe I'll

mention in the comment or somewhere V

equals to SPF 1 and then maybe

mentioning that it is coming from Google

servers. Okay, I don't have the exact

syntax right now, but basically what it

will do is that email coming from Google

or Gmail is only allowed, not anyone

else can use it. And then there is a DKM

record also for avoiding any spams or

any you know cyber threats. So that is

also there. It is used for multiple ways

but yeah text records is pretty much for

setting up your ownership or authority

and showing to the world that basically

who has the ownership of this domain and

who can send legit emails. So if uh you

know some emails are getting sent on a

spam folder that means the text record

is not set up. You might have seen that

if you want to set up notion or slack on

your domain they give you these kind of

text entries to be added into your DNS

record so that it could be legitimized

the use of your uh Gmail and your Gmail

account can be legitimized via notion or

slack. So that is what is text record is

used for. Obviously it is not the only

use case but yeah this is one of the use

cases for it. So friends, a perfect way

to summarize this uh video is to

understand what kind of issues you might

face related to DNS records. And if you

are put into a situation where you have

to troubleshoot a issue or answer a

scenario based question, then you can

apply this logic. Now, not every issue

is a DNS issue. But if you are put into

that situation, this could be your first

troubleshooting step. And by the way,

there are other records as well. For

example, Aliyah's name which can be used

at a root domain. So root domain can be

example.com as well. Example.com is your

root domain. You can also write www. But

because you can't have root domain as a

CNAME then you have to use it in here.

So these kind of questions might come.

The interviewer might ask you can you

use root domain as a CNAME record then

you should say no we we can't use it we

have to use a subdomain here. Okay which

is different from the root domain.

Similarly if there is any website which

is not to be found or it is completely

connection failed then pretty much it

could be an A record issue. Your IP

address is in problem. If there is

latency involved then it could be that

your IPv6 is not configured or maybe

your system expects you to send IPv6

address first but because it is not

there it is taking time to fall back to

IPv4. CNAME and NS records are uh

generally when you get issues like

domain not found. It could be that your

load balancer uh has changed or your NS

record has changed you have migrated

from one domain to another domain. So

you have to focus on these kind of

records then. And for SOA and text it is

mostly like it is working for me but it

is not for working for you not text but

SOA and TTL. Okay. These kind of records

come into play when it is not working

for me but it is working for you. It is

working for some people. It is not

working for some people. Then it could

be a possibility that your SOA and your

TTL records are not rightly populating

the latest records. That is something

which you have to look. For example the

refresh. If refresh is 1 hour or 1 day

then it might be the problem or also

time to live we have already discussed

about it. If it is too high then again

it might be that it is not reflecting

the changes quickly. And for the last

one a good example could be if the

emails are landing on the in the

spamming folder spam folder then pretty

much we have not configured the text

records and mentioning the correct

Google servers or Gmail servers which

will be legitimizing these emails coming

from our domain. Okay. So these are few

scenarios. Obviously DNS in itself is a

big field. People spend their whole life

doing DNS and I am nobody to uh claim

any expertise in it. But I felt that

this could be a good continuation to our

previous DNS video. There is so much

depth into it that uh I might have made

if I made any mistakes then do correct

me in the comment section. I have tried

to simplify it as much as possible for

you. But the idea is we have to now move

from you know a beginner or a mid-level

engineer to a senior architect or a

senior consultant and these kind of

discussions will help you look like an

experienced professional and feel like

an experienced professional because

you're not talking basics you are going

into the depth of things and this will

be the theme of this channel going

forward. So I hope this was a useful

video guys. Do hit a like, share,

comment. It helps the channel to grow.

And yeah, let me know what you would

want to learn next. And until next time,

keep learning, keep sharing, and keep

exploring. Bye for now.