DNS Records

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Күн бұрын

In order to find resources on the network, computers need a system to look up the location of resources. Check out / itfreetraining or itfreetraining.com for more of our always free training videos. This video looks at the DNS records that contain information about resources and services on the network. The client can request these records from a DNS server in order to locate resources like web sites, Active Directory Domains and Mail Servers just to name a few.
ITFreeTraining.com/handouts/dn...
In this video
This video will look at the following DNS records:
Host (A and AAAA): Contains IP Addresses for IPv4 and IPv6 hosts
Alias (CNAME): Works just like a shortcut for files except for DNS records.
Mail Exchange (MX): Holds the address of mail servers for that domain.
Service Record (SRV): Holds the address of services on the network. E.g. Active Directory DC's.
Start of Authority (SOA): Contains information and configuration for a zone file.
Name Server (NS): Contain the address of other DNS servers for that zone.
Pointer (PTR): Reverse look up record allowing a hostname for an IP Address to be look up.
Host (A and AAAA)
The host record is used to store the address of a hostname. "A" is used for IPv4 and AAAA (Quad A) for IPv6. These can be created manually in DNS or if dynamic DNS is enabled and the client can register its hostname and thus its IP Address with the DNS server.
Alias (CName)
A canonical name or CName record provides an alias service in DNS. A CName effectively points to another A or Quad A record. When the client requests the hostname that is contained in the CName, they are given the IP Address that is contained in the A record or Quad A record. The advantage of a CName is that it can provide a simple name to the user rather than a more complex server name. For example, instead of having to remember FS27 for the local file server, a CName of FS could be used to point towards the server FS27. CName's can also be used to transparently redirect network traffic. For example, if you changed you mind and wanted to redirect the user to FS28 you would only need to change the CName record to point to FS28 rather than FS27. It should be remembered that the old record may exist in the client cache and may take some time to expire.
Mail Exchange (MX)
The mail exchange record contains a mail server that is able to process mail for that domain name. When a mail server wants to deliver mail, it will perform a DNS lookup asking the DNS server for an MX record for that DNS Domain name. The mail server will then attempt to deliver mail to that server. The mail server does not need to have the same DNS name as the mail that is being delivered, it simply needs to understand how to process mail for that DNS domain name.
The MX record also has priority value that can be configured. If two or more MX Exchange records exist for the same DNS Doman name, the MX record with the lowest priority will be tried first. If this fails, the MX record with the next lowest value will be tried until the mail is delivered. Often large companies will have multiple mail severs for incoming mail. In some cases, these additional mail servers may be located on different sides of the globe in case there is a long network outage.
Service Record (SRV)
Service records allow clients on the network to find resources on the network. Active Directory creates a number of service records in DNS to allow clients to find resources like Domain Controllers. This is why Active Directory cannot operate without DNS. A single service record has a number of data fields associated with it. These include, service, target, port and priority. Service records are normally created automatically by applications assuming that your DNS server allows dynamic updates.
Start of Authority (SOA)
There is one start of authority record (SOA) for each zone. Even though the SOA is technically a DNS record, essentially modification of the SOA record is performed through the properties of the DNS zone. Looking at the data in the SOA record, you can configure options for the zone like the primary name server for that zone (DNS servers that hold the master records for the zone), the e-mail address of an administrator, serial number (Incremented each time a change is made in the DNS zone) and the refresh time for the zone (How often a secondary zone should query a master for changes).
Video description to long for KZfaq. For full description please see itfreetraining.com/70-642/dns-...
See / itfreetraining or itfreetraining.com for our always free training videos. This is only one video from the many free courses available on KZfaq.
References
"MCTS 70-640 Configuring Windows Server 2008 Active Directory Second edition" pg 458 -- 459
"Installing and Configuring Windows Server 2012 Exam Ref 70-410" pg 236-237
"SRV record" en.wikipedia.org/wiki/SRV_record

Пікірлер: 176

@itfreetraining 10 жыл бұрын

Thanks, glad to hear that you like the videos.

@itfreetraining 10 жыл бұрын

No problem at all. Thanks for watching.

@farukhshaikh2672 9 жыл бұрын

Its just due to your videos i am able to understand windows servers. May God bless you guys.

@itfreetraining 9 жыл бұрын

Farukh Shaikh Thanks very much, glad we could help you

@JDBoelter 6 жыл бұрын

Good presentation - clearly miked and clearly delivered, good plain English explanations. I feel as if I understand SOA and NS records much better now. Thanks!

@itfreetraining 6 жыл бұрын

You're most welcome! Thank you for your kind feedback. :)

@kittnlogic 4 жыл бұрын

Thank you for the clear and concise lesson! So helpful!

@doubledogdare610 10 жыл бұрын

Thanks Sir! I have been looking for somthing that can help me with my mail server but finally! I didnt know that i was using the wrong record...

@jdphd123 10 жыл бұрын

I am so glad that you made available this information and video.* Also the narration and manner used.

@itfreetraining 10 жыл бұрын

Thanks very much. Glad to hear that you like the video.

@user-tf9lx9iy1s 9 жыл бұрын

very good ,this lesson explain the knowledge very well. thanks

@itfreetraining 9 жыл бұрын

Thanks very much. Glad we could help.

@richardcummins3649 7 жыл бұрын

You have a collection of great videos. Very informative!

@itfreetraining 7 жыл бұрын

Thanks for the great feedback! We appreciate you choosing ITFreeTraining!

@waseemhasan5372 2 жыл бұрын

Much appreciated the graphics and explanation. Keep up the amazing work!

@itfreetraining Жыл бұрын

Much appreciated!

@onlyeyeno 3 жыл бұрын

This is a good and very well presented video and I'm very grateful for You making and sharing it. That said I think it could have been even better if it had used more "graphical slides", if the type You used when explaining (clarifying) the "MX record". Showing an "over view" of where (in the network) the different records would be "held".And how they would "querried and answer" to fulfill their function is something I believe would facilitate learning and grasping the context of, and relation between the different records. Again many thanks for making and sharing this excellent content Best regards.

@sordodikra5129 7 жыл бұрын

You are truly amazing. THANK YOU.

@itfreetraining 7 жыл бұрын

You're welcome! Thanks for the amazing feedback. :)

@andreigheorghe5402 11 жыл бұрын

I love your presentations.

@mcsephiroth1312 3 жыл бұрын

Thank you for this explanation. I understood it much better than Google IT Training's explanation.

@itfreetraining 2 жыл бұрын

You are welcome!

@adamwilkinson007 11 жыл бұрын

Thanks guys this is brilliant your going to help me get me through my exams for 70-410 :-)

@abhijeetnegi6484 3 жыл бұрын

i still watch ur awesome expalnations, and it is jus so good.

@sergei4517 4 жыл бұрын

Excellent right to the point explanations. Thanks a lot!

@itfreetraining 4 жыл бұрын

Glad it was helpful!

@CLAIREdujardin 10 жыл бұрын

Very clear explanations. Keep up the good work !

@itfreetraining 2 жыл бұрын

Thanks for watching.

@MrPrasad730 10 жыл бұрын

Very clear explanations. Keep up the good work ! thx

@itfreetraining 10 жыл бұрын

Thanks very much. More videos to come.

@greatsky8226 2 жыл бұрын

Competent video with brilliant rhetoric.

@itfreetraining 2 жыл бұрын

Thanks very much.

@itfreetraining 11 жыл бұрын

Thanks Adam! Good Luck taking them

@ramziboutaoua3298 3 жыл бұрын

You got the art of explaining, you are the best

@TebogoMotlhale 3 жыл бұрын

Yeah, he is best by FAR. The others tend to fall into the trap of starting off by using too many SIMPLE analogies and then when the topic goes deeper, it gets harder for them to find perfectly equivalent concepts in the analogy, to keep using that analogy in a manner that is STILL relevant/meaningful to the topic 😁

@ramziboutaoua3298 3 жыл бұрын

@@TebogoMotlhale exactly, some times calling things by their real names works much better then exaustive analogies

@lakminarathnayake2165 4 жыл бұрын

Great Knowledge Video of DNS records I ever see

@hisatnam 4 жыл бұрын

Wow, I liked it. Thanks for sharing this with us.

@itfreetraining 2 жыл бұрын

Thanks for watching.

@itfreetraining 10 жыл бұрын

Thank you.

@itfreetraining 10 жыл бұрын

Thanks very much.

@DillonMinasian 11 жыл бұрын

Great Video, helped explain a lot. Thanks :)

@eavincentg 6 жыл бұрын

Thank you. Excellent tutorial!

@itfreetraining 6 жыл бұрын

Thank you for your great feedback!

@cskillet2003 4 жыл бұрын

Great video on common resource records!

@itfreetraining 4 жыл бұрын

Thanks!

@patrickjohnyap2112 10 жыл бұрын

very well said :) thanks for all the videos

@raghuveershetty2922 8 жыл бұрын

nice clear explanation with examples and with easy english

@itfreetraining 8 жыл бұрын

Thanks!

@MsAshutosh123 3 жыл бұрын

Can you make a video on different types of http error codes in the same whey.your videos are simple and easy to understand

@TheAmazeer 6 жыл бұрын

Great job.. a value added would have been to show Dns configuration but maybe you did it on another video

@albixhako1727 3 жыл бұрын

Thank you. Very simple and informative way.

@itfreetraining 2 жыл бұрын

Glad it was helpful!

@bulelanicutalele7940 7 жыл бұрын

Helpful indeed, clear explanation

@itfreetraining 7 жыл бұрын

Thanks for the great feedback and for watching!

@sencadas32 8 жыл бұрын

Congratulations! Nice video!

@itfreetraining 8 жыл бұрын

+Vinicius Thank you very much, we're glad to hear your feedback.

@mez1486 5 жыл бұрын

I do everything right but the SPF record can't be verified so frustrating!

@chrisharrid5725 3 жыл бұрын

Really helped me. Thanks for that.

@itfreetraining 2 жыл бұрын

You're welcome!

@hemang81 6 жыл бұрын

Thanks...It's been very very informative..!!

@itfreetraining 6 жыл бұрын

You're very welcome!

@balajidhatchanamoorthy3198 8 жыл бұрын

superb,its really useful to me to understand thanks a lot

@itfreetraining 8 жыл бұрын

+Balaji Raina You're most welcome.

@boatengokyere-darko3806 11 жыл бұрын

I love it soo much, Cheers.

@enizi1 9 жыл бұрын

Thank you very much ,,it is very helpful.

@itfreetraining 9 жыл бұрын

Thanks, glad we could help.

@GunelMammadova93 3 жыл бұрын

thanks for the video! Learned a lot from it

@itfreetraining 2 жыл бұрын

Glad it was helpful!

@arvindpal8070 3 жыл бұрын

Thanks to explain DNS record in easy to understand

@itfreetraining 2 жыл бұрын

It's my pleasure

@ramireddy5071 7 жыл бұрын

excuse me sir i have a doubt what do you mean by resource records?(my exam question) ca i write your explanation for that question thank u sir

@chandranaggmchandranag8818 3 жыл бұрын

Finally found this Thank you sir

@itfreetraining 2 жыл бұрын

Thanks for watching.

@felixmintah8632 10 жыл бұрын

Great video

@itfreetraining 10 жыл бұрын

Thanks very much.

@leo-rq2ei 5 жыл бұрын

Nicely done 👏👏

@itfreetraining 5 жыл бұрын

Thanks!

@itfreetraining 10 жыл бұрын

Thanks.

@bryanmendoza3919 4 жыл бұрын

great it will help me on how to recognize those records in DNS

@itfreetraining 4 жыл бұрын

Glad we could help.

@shiwang4809 2 жыл бұрын

So helpful!

@itfreetraining 2 жыл бұрын

Glad it was helpful!

@netaishvasistha9875 10 жыл бұрын

Great Video very well Expained Thx

@itfreetraining 10 жыл бұрын

Thanks very much and thanks for watching.

@precisionit1422 10 жыл бұрын

Very good videos with full clarity.Well done sir but no videos on AD DS backup and restore.pls upload sir.

@itfreetraining 10 жыл бұрын

Sorry about that, will get those videos done when we can.

@shubhamjoshi_SELabs 8 жыл бұрын

Excellent! Thank you

@itfreetraining 8 жыл бұрын

+shubham joshi We're glad you think so! You're welcome and thank YOU for watching!

@alihaleem2705 6 жыл бұрын

thanks again .. great video

@itfreetraining 6 жыл бұрын

You're welcome!

@bder88 4 жыл бұрын

thx alot , great video

@TahaIsmailCanada 10 жыл бұрын

Thanks so much

@itfreetraining 10 жыл бұрын

No problem at all. Thanks for watching.

@Thepankaz1 7 жыл бұрын

For CNAME Record where does it maintain ip for web1, cname stors alias but how is actual ip is obtained for web1, is another call made to another dns server which maintains a A record or same server maintains both CNAME and A record.

@itfreetraining 7 жыл бұрын

The resolver sees that it's a CNAME and begins its search over again at the root domain level. For example, if there is a DNS zone as follows: NAME TYPE VALUE -------------------------------------------------- bar.example.com. CNAME foo.example.com. foo.example.com. A 192.0.2.23 when an A record lookup for bar.example.com is carried out, the resolver will see a CNAME record and restart the checking at foo.example.com and will then return 192.0.2.23.

@nifink.antony6953 4 жыл бұрын

Amazing..Nice

@thaernidal9832 9 жыл бұрын

it's helpful thank you

@itfreetraining 9 жыл бұрын

You're welcome, glad the video was helpful!

@gonzalotrepiana6628 10 жыл бұрын

thanks so much!!

@Rassamaxa1000 11 жыл бұрын

very good!!thanks

@YouSsefDjOGeekOfficial 6 жыл бұрын

well explained thanks !

@itfreetraining 6 жыл бұрын

You're very welcome!

@mattia7737 3 жыл бұрын

thank you very much it really help me

@itfreetraining 2 жыл бұрын

Thanks for watching.

@srirama4580 9 жыл бұрын

i have a live scenario.. Windows 2012 installed with AD and Dns. Standard configuration. noticed if i nslookup ip and hostname . all good if i use the fqdn there is 2 request time out and a reply. if i use fqdn with dot at the end its good. please help Thanks in advanc

@itfreetraining 9 жыл бұрын

Sri Rama I am not sure what the problem is here. Windows will normally add the dot at the end so you don't need to worry about it. It is strange that it requires it to be there. Have you configured your own root servers or are you forwarding the requests to your ISP?

@roxriver91 8 жыл бұрын

thank you, excellent.

@itfreetraining 8 жыл бұрын

+roxriver91 You're welcome! Thanks for watching.

@hunkmujeeb 6 жыл бұрын

I am unable to ping Server 2K8r2 to win 7 host. I have created DNS forward and reverse records and allow ICMP also.

@itfreetraining 6 жыл бұрын

What happens when you try to ping the IP address directly?

@lucha_ftw 6 жыл бұрын

Great stuff

@itfreetraining 6 жыл бұрын

Thank you!

@Mangokyaw Жыл бұрын

I am so confused.. what are the differences between the MX, pop3, Imap4, snmp, smtp?

@itfreetraining 10 ай бұрын

DNS MX (Mail Exchanger) Record: MX records are DNS records that specify the mail servers responsible for receiving email messages on behalf of a domain. MX records help route email messages to the correct destination by pointing to the mail servers' hostnames or IP addresses. MX records are essential for email delivery, as they determine where incoming email messages should be delivered within a domain. POP3 (Post Office Protocol version 3): POP3 is an email retrieval protocol used by email clients to retrieve email messages from a mail server. POP3 typically downloads email messages to the client's device, removing them from the server. This means that emails are stored locally, and changes made on the client do not affect the server's copy. POP3 is commonly used for downloading emails to a single device, like a computer. IMAP4 (Internet Message Access Protocol version 4): IMAP4 is another email retrieval protocol used by email clients to access email messages stored on a mail server. Unlike POP3, IMAP4 allows multiple devices to access the same mailbox simultaneously and keeps emails synchronized across all devices. Changes made on one device are reflected on the server and other devices. IMAP4 is suitable for users who want to access their emails from multiple devices and keep them synchronized. SNMP (Simple Network Management Protocol): SNMP is a network management protocol used for monitoring and managing network devices like routers, switches, and servers. SNMP allows network administrators to collect data and manage devices remotely by querying and configuring settings on network equipment. It is not directly related to email or DNS but is essential for network management and monitoring. SMTP (Simple Mail Transfer Protocol): SMTP is an email sending protocol used to send outgoing email messages from a client to a mail server or from one mail server to another. SMTP is responsible for routing and delivering email messages to their intended recipients. It works together with MX records and other email protocols. SMTP is essential for the delivery of email messages across the internet. In summary, DNS MX records help route email messages, while POP3 and IMAP4 are email retrieval protocols for accessing email messages stored on mail servers. SNMP is a network management protocol, and SMTP is an email sending protocol responsible for delivering email messages. These protocols serve different roles in the email and network communication process.

@kedmnc895mna 6 жыл бұрын

This is great.

@itfreetraining 6 жыл бұрын

Excellent, thanks for the wonderful feedback.

@nithinkg2880 8 жыл бұрын

great video

@itfreetraining 8 жыл бұрын

+Nithin Kg Thanks!

@Tymonello 5 жыл бұрын

thanks, it is helpful

@itfreetraining 5 жыл бұрын

Thank you for watching!

@syedjunaid7846 4 жыл бұрын

4:10 did you mean when a DNS server has an email it needs to end it needs to locate a mail server

@itfreetraining 4 жыл бұрын

It is a little confusing. So essentially lets say that an e-mail server wants to send an e-mail to example.com. In order to do this, it needs to send the e-mail to the example.com mail server. So it performs a look up to find out where example.com mail server is. Essentially gets the MX record for example.com. The mail server then contacts the example.com mail server and transfers the mail to it.

@clovisgrenier 6 жыл бұрын

THANK YOU

@itfreetraining 6 жыл бұрын

You're very welcome!

@keplerdevelopers9636 7 жыл бұрын

Why there is not MX record when I nslookup www.hotmail.com ?

@itfreetraining 7 жыл бұрын

Hotmail seems to want to use a CNAME record vs a traditional MX record. That's probably why.

@Ragatokk 8 жыл бұрын

How do I set up my server when I have it on a subnet? Say my external ip is 84.22.1.331 but my local ip is 192.168.1.2. How would I set up my www.website.com to be sendt to the server with the local ip of 192.168.1.2 ?

@itfreetraining 8 жыл бұрын

+Ragatokk Your server is using a private IP Address. So you need to configure your home router to forward web traffic to that server. So in your router, forward port 80 to 192.168.1.2

@Ragatokk 8 жыл бұрын

Thanks, but how do I do it when I have two servers on the same network?

@itfreetraining 8 жыл бұрын

+Ragatokk Multiple web sites can share the same IP Address. The web server should use the incoming DNS to work out what web site it is. However, you will not be able to have to servers using the same port unless you have two different public IP Addresses.

@shihabuddinnori8236 7 жыл бұрын

thanks thanks thanks thanks

@eleftheriosiliopoulos8796 8 жыл бұрын

it is valid 100% for the 70-411.

@itfreetraining 8 жыл бұрын

+LEF ISOS Excellent, we're always excited to confirm our content lines up with the Microsoft exams.

@messiassantos5140 5 жыл бұрын

Thank you I mean it u helped me

@itfreetraining 5 жыл бұрын

You're most welcome, thanks for watching!

@jgwood89 8 жыл бұрын

When you said "another A record", did you mean another Alias Record?

@itfreetraining 8 жыл бұрын

That's correct.

@jgwood89 8 жыл бұрын

Thank you. Also, since PTR works the opposite of A records essentially, does that mean it also works the opposite of CNAME records?

@itfreetraining 8 жыл бұрын

The A record maps a name to one or more IP addresses, when the IP are known and stable. The CNAME record maps a name to another name. It should only be used when there are no other records on that name. The A name must resolve to an IP, the CNAME and ALIAS record must point to a name. To answer your question: No, PTRs are not the opposite of CNAMEs. CNAMEs are similar to aliases and point to another hostname vs an A record which points to an IP.

@user-oq1id3sv9d 6 жыл бұрын

thanks

@itfreetraining 6 жыл бұрын

You're most welcome!

@vjnvisakh 5 жыл бұрын

nice.

@mohamedabas942 9 жыл бұрын

i dont know the use of this stupid service record .. its allways spam filessrv like this ::::::: Firefox Setup 16.0.1SrvSrvSrv .. and i dont know how to stop it .. it creat about 50 - 74 file when i start any program or click any icon :S any one can help me in this ?

@itfreetraining 9 жыл бұрын

Mohamed Abas I have not heard of this before. If you know which computer it is coming from I would do a check for the computer to see what software is installed. perhaps run a packet sniffer on the computer to work out which software is creating them. Perhaps it is Malware so I would do a check for that as well.

@ziaullah9541 8 жыл бұрын

awesome

@itfreetraining 8 жыл бұрын

Thanks!

@bogdanM29 5 жыл бұрын

there's a difference between A Records and CName, CName can't be used for naked domain names.

@itfreetraining 5 жыл бұрын

CName are like a shortcut like that used in the file system. For example, if you had www.itfreetraining.com and itfreetraining.com you could create a CName to like one to the other. This way you only have one A record making it easier to manage.

@DzikuS-km8he 8 жыл бұрын

Nice

@itfreetraining 8 жыл бұрын

Thanks!

@kevinportillo1971 6 жыл бұрын

Out of everyhting from TCP/IP if find this topic the most difficult to remember !!!!

@itfreetraining 6 жыл бұрын

Networking isn't always intuitive so stick with it!

@Metallnsanity87 5 жыл бұрын

1.25 video speed is best

@raghuveershetty2922 8 жыл бұрын

if they start training institute in indian many students will benefit

@dean6845 8 жыл бұрын

I'm studying computer networking for few weeks using web pages and youtube and I mostly encountered courses with indians (I hope that's how you call people from india) so I'm not sure if they even need teacher, since they are teacher itself :D Kidding, but sometimes they really are "know-it-all". Great video and explanations :) Peace

@rothscliff6086 4 жыл бұрын

teaches better than Uni lol

@itfreetraining 4 жыл бұрын

Thank you.

@mahdiehshahhosseinian3558 2 жыл бұрын

so confusing

@itfreetraining 2 жыл бұрын

What do you find confusing?

@michaelsiengo1 2 жыл бұрын

Am I the only one who thinks DNS is confusing as hell been trying to learn it for about a month

@itfreetraining 2 жыл бұрын

DNS can be difficult at first, is there anything in particular you are having problems understanding?

@CorporateMajdoorTrader 2 жыл бұрын

Such a vague explanation

@itfreetraining 2 жыл бұрын

This is a pretty old video now. It helps if you watch the other DNS videos as well. We generally make the videos now so they can be watched by themselves. Is there anything in particularly you are having trouble understanding.