DNS Records

DNS Records

In order to find resources on the network, computers need a system to look up the location of resources. Check out http://YouTube.com/ITFreeTraining or http://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.

http://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 YouTube. For full description please see http://itfreetraining.com/70-642/dns-…

See http://YouTube.com/ITFreeTraining or http://itfreetraining.com for our always free training videos. This is only one video from the many free courses available on YouTube.

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” http://en.wikipedia.org/wiki/SRV_record

50 Comments

  1. No One on February 6, 2021 at 2:58 am

    thx alot , great video



  2. Farhan Tanvir on February 6, 2021 at 2:58 am

    Thank you.



  3. Clovis Grenier on February 6, 2021 at 2:59 am

    THANK YOU



  4. TheAmazeer on February 6, 2021 at 3:00 am

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



  5. Nifin K. Antony on February 6, 2021 at 3:03 am

    Amazing..Nice



  6. Pankaj kumar on February 6, 2021 at 3:03 am

    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.



  7. Serge I on February 6, 2021 at 3:03 am

    Excellent right to the point explanations. Thanks a lot!



  8. Bryan Mendoza on February 6, 2021 at 3:07 am

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



  9. Mattia on February 6, 2021 at 3:10 am

    thank you very much it really help me



  10. Kevin Portillo on February 6, 2021 at 3:10 am

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



  11. _He!senb3rg_ on February 6, 2021 at 3:10 am

    Great stuff



  12. J W on February 6, 2021 at 3:12 am

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



  13. Bogdan Moldovan on February 6, 2021 at 3:12 am

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



  14. Kepler Developers on February 6, 2021 at 3:13 am

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



  15. Hunk Mujeeb on February 6, 2021 at 3:14 am

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



  16. sordo dikra on February 6, 2021 at 3:18 am

    You are truly amazing. THANK YOU.



  17. Richard Cummins on February 6, 2021 at 3:18 am

    You have a collection of great videos. Very informative!



  18. Bulelani Cutalele on February 6, 2021 at 3:20 am

    Helpful indeed, clear explanation



  19. leo on February 6, 2021 at 3:21 am

    Nicely done 👏👏



  20. Messias Santos on February 6, 2021 at 3:22 am

    Thank you I mean it u helped me



  21. Jai Shree Gupta on February 6, 2021 at 3:24 am

    Thank you friend ! it was really nice Vedio. I have one more scenario question I need your help : I have two DC 1 and DC2 . and DC1 is primary domain and DC 2 is secondary detail.  I have two types of authentication services 1) Service account authentication 2) General user authentication. I wanted to give service account authentication load on the DC1 and general authentication load should be authenticated by DC2. may I know the step by step configuration to do that ? please share me vedio if possible. thanks in Advance! Regards,Jaishree Guptapinko.best@gmail.com+91-9008510832



  22. Richard Cummins on February 6, 2021 at 3:26 am

    I recommend dynu.com for free DNS record hosting. They offer hosting for all DNS records mentioned in the video for free: A, AAAA, MX, SRV, SOA, CNAME, NS as well as TXT, DKIM etc.



  23. Albi Xhako on February 6, 2021 at 3:26 am

    Thank you. Very simple and informative way.



  24. lakmina rathnayake on February 6, 2021 at 3:27 am

    Great Knowledge Video of DNS records I ever see



  25. Josh Mora on February 6, 2021 at 3:27 am

    1.25 video speed is best



  26. Emily Martinez on February 6, 2021 at 3:29 am

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



  27. abhijeet negi on February 6, 2021 at 3:29 am

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



  28. James Boelter on February 6, 2021 at 3:31 am

    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!



  29. syed junaid on February 6, 2021 at 3:31 am

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



  30. Chandranag Gm Chandranag on February 6, 2021 at 3:32 am

    Finally found this
    Thank you sir



  31. Rawia Larbi on February 6, 2021 at 3:38 am

    thanks



  32. OMGKITTENSMEOW on February 6, 2021 at 3:38 am

    This is great.



  33. Everett Vincent on February 6, 2021 at 3:39 am

    Thank you. Excellent tutorial!



  34. Hemang Vyas on February 6, 2021 at 3:39 am

    Thanks…It’s been very very informative..!!



  35. Ali Haleem on February 6, 2021 at 3:39 am

    thanks again .. great video



  36. Tymonello on February 6, 2021 at 3:39 am

    thanks, it is helpful



  37. Ashutosh Pal on February 6, 2021 at 3:40 am

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



  38. Visakh Vijayan on February 6, 2021 at 3:42 am

    nice.



  39. ramzi boutaoua on February 6, 2021 at 3:42 am

    You got the art of explaining, you are the best



  40. DzikuS 1337 on February 6, 2021 at 3:44 am

    Nice



  41. Thomas Jones on February 6, 2021 at 3:48 am

    Your explanation of MX was very confusing.



  42. cskillet2003 on February 6, 2021 at 3:49 am

    Great video on common resource records!



  43. Rothscliff on February 6, 2021 at 3:50 am

    teaches better than Uni lol



  44. SHIHABUDDIN NORI on February 6, 2021 at 3:50 am

    thanks thanks

    thanks thanks



  45. Satnam Singh on February 6, 2021 at 3:51 am

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



  46. Mez 14 on February 6, 2021 at 3:51 am

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



  47. Chris Harrid on February 6, 2021 at 3:52 am

    Really helped me. Thanks for that.



  48. Gunel Mammadova on February 6, 2021 at 3:52 am

    thanks for the video! Learned a lot from it



  49. Youssef Trabelsi on February 6, 2021 at 3:54 am

    well explained thanks !



  50. rami reddy on February 6, 2021 at 3:57 am

    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