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

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

house. Okay. So just a gist of what is DNS. We have a basic video on DNS where

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

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

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

simple. It does what DNS stands for at a high level which is it has the name of the domain. So we'll take

the domain. So we'll take www.example.com

www.example.com throughout uh this video and we will see how different uh records map to this particular domain. So www.example.com

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

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

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

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

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.

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

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

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

name. It is nothing but a forwarding address. you are forwarding requests

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

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,

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

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

different levels. So you first of all have a root domain. Okay. So when we type www.google google.com there is

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

destination. This record is like a constitution. It tells whatever this

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

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

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

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

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

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

slack. So that is what is text record is used for. Obviously it is not the only

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,

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

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

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

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

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

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

scenarios. Obviously DNS in itself is a big field. People spend their whole life

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

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

forward. So I hope this was a useful video guys. Do hit a like, share,

video guys. Do hit a like, share, comment. It helps the channel to grow.

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.

exploring. Bye for now.