Welcome to the ITfreeTraining video on DNS records. This video will go through the basic
DNS records that are available and also look at some of the less common DNS records. By
the end of this video you will not only have a better understanding of DNS records that
are available, but you will also be able to create your own. Without further ado, I will
change to my Windows 8 computer running Remote Server Administration Tools.
First of all, I will open DNS manager. To do this, open charms by moving the mouse to
the top right of the screen and then select search. DNS Manager and other tools are found
under Administrative Tools. Once Administrative Tools has opened, I need
to find the shortcut for DNS Manager and run it. When DNS Manager opens, it will first
ask which DNS server I want to connect to, in this case I want to connect to NYDC1 which
is my Domain Controller and DNS server for the New York network.
To look at the DNS records, I will expand down until I get to forward look up zone for
ITfreeTraining.local. I will look at creating DNS records later on in this video, but the
first DNS records that I want to look at are accessible through the properties. To access
the properties, I will right click the zone and select properties.
In properties, I next will select the tab Start of Authority. The Start of Authority
tab is used to make changes to the SOA record contained in the zone. Even though the SOA
record is a DNS record contained in the zone file like the other records, in order to make
changes to it you need to perform these changes from the properties of the zone. There can
only be one SOA record per zone so it makes sense to have changes made to it from the
properties of the zone. Doing it this way makes it a little more user friendly.
I won’t go through all the options here as I go through a lot of these options in
the video DNS zones. You can see the setting primary server. This indicates a server that
holds the primary zone. In the case of Active Directory Integrated zones, this can be a
Domain Controller that has DNS installed on it. If you remove any DNS servers from your
network you should check this setting to ensure that it is pointing to a valid DNS server.
The next option below is the link to a responsible person record. For this field all you need
to enter in is an e-mail address of the person looking after this zone. The trick with this
one is to change the @ sign to a period. If you press the browse button DNS will search
of a responsible person or RP record. It is not recommended that you use RP records as
some mail servers can’t interpret them correctly. Below this are the settings that are used for
replication and how long records last before they expire.
The next set of records that are configured in the properties are the Name Server records
which are done on the Name Server tab. You can see here that there are 3 name servers
defined. Name servers are DNS servers that are considered to be able to give authority
or the best source of answers for that zone. I covered this topic in more detail in the
DNS zones videos. For this video, understand that you can add and remove Name Server records
using this tab. If I exit out of here, I can now create some
DNS records in the zone. The first record I will create is a host record by right clicking
the zone and selecting “New Host”. An A record is used with IPv4 while a quad
A is used with IPv6. You don’t need to worry about deciding which one to create as the
interface will choose the correct record based on the IP Address that you enter.
In this case I will enter in a host address for the New York router and an IPv4 IP address
for the router. Since the router does not register itself automatically in DNS using
dynamic updates and, even if it did, it would not support secure updates since it is not
a domain member, this is a good choice for a manual host name.
Notice also the tick box “Create associated pointer record” is ticked. This will automatically
create a pointer record in the reverse look up zone for this host record. This will allow
reverse look up’s to be perform on the IP Address which are great when troubleshooting
problems. Once I press add host the record will be added
including the pointer record. If either record could not be created I would get an error
message, for example if no reverse look up zone had been created to store the pointer
record in. Once I confirm the record has been created,
next I will create the same host entry for the IPv6 address. The procedure is the same,
enter in the host name and IP Address and press add host.
Just like last time I will get a dialog box telling me the host record was created. I
will now exit out of here and look at some of the other DNS records that can be created.
If I right click on the zone file and select New Alias, this will create an alias record.
An alias record is simply an alternative name that can be used to access that record. Let’s
consider two servers that have a host record associated with them. For the user, accessing
the server using SRV1 or SRV2 means the user needs to know which service is on which server.
C names can be created for each service. For example, a CName could be created for mail
and www. Now when the user attempts to resolve mail
or www they will be directed to SRV1. If an FTP service was added to SRV2, it would be
a simple matter to create a CName that points to SRV2.
The advantage of this is that if SRV1 was to be become unavailable or retired it would
be a simple matter to install the mail and web server on SRV2 and change the CName records
to point to this server instead. You can see that using alias records like these you can
transparently redirect users to resources as required without them having to change
any configuration on their computer. I will now create an alias record for mail1
that will direct any queries for mail1 to SRV1. To do this, all I need to do is enter
the alias as mail1 and then browse to SRV1. Once I am happy with the record, I can press
o.k. and the record will be created. To test the DNS record out, I will open a
command prompt by opening charms, selecting search and then selecting the command prompt
icon. From the command prompt I will ping mail1.
Notice that mail1 is resolved to an IP Address and the server is responding back to the ping
request. If you look closely at the address that was
resolved, notice that SRV1 was resolved. The DNS server automatically substituted SRV1
in place for mail1. All this was done without any input from the user and can be changed
on the DNS server at any time as required.
The next record that I will look at is the MX Record. In this example I will create two
MX records as shown. These two records will be created in the ITFreeTraining.com zone
One will have the priority of 5 and the other will have a priority of 10. This means that
the left MX record will be used by default. If this server is not available, the second
MX record on the right will be used. I will now go back to my Windows 8 computer and have
a look at how to create these MX records.
First of all, I will expand down until I get to the forward look up zone ITFreeTraining.com.
To create the first MX record, right click the zone and then select the option “New
Mail Exchanger”.
For the fully qualified domain name I will enter in mail1. Since the DNS record mail1
will exist in the same domain name, that is it will exist in ITfreeTraining.com, I only
need to enter in the host name. You could also select a host record that is in another
domain name, this would work as well.
For the mail server priority I will change this value to 5. It is also important, since
this DNS record is being created manually, to ensure the tick box “Delete this record
when it becomes stale” is not ticked. If this tickbox is ticked, when scavenging is
perform this DNS record will be removed and thus clients on the internet will not be able
to locate the e-mail server.
Once the MX record has been created, the next step that I will do is create the next MX
record using the same process. Notice that for the fully qualified domain name, I can
also use an IP Address. In this case I have used a google IP address as I don’t have
an e-mail server set up at present. I will leave the priority on the default of 10 and
create the DNS record.
The last step that I need to do is create a host record for mail1 since it does not
exist. To do this, I will right click on the zone and select New host. For the name I will
enter in mail1 and then enter in an IP Address for it. Once again I will use a google IP
address as I do not have an e-mail address setup at present.
Once the “A record” is created, the two MX records are ready to be used. In some cases
you may need to create a less commonly used DNS record. To do this, right click the DNS
forward look up zone and select Other New Records.
This will give you a list of all the less common DNS records that can be created. It
is a just a matter of selecting the DNS records that you want to create. In this case I will
select the option from the list Service Location as an example. You can see that once you select
the DNS record that you want and press the button create record, it is a simple matter
to fill out the details for the DNS record.
Well that covers it for creating DNS records in Windows. I hope you have found this video
useful. Please feel free to check out our other free videos on DNS and other IT topics.
Thanks for watching and see you next time.