Exam Ref 70-411 Administering Windows Server 2012 R2 (2014)

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Creating and configuring DNS resource records

The DNS server in Windows Server supports a very wide variety of resource records, but the ones that most people have to deal with are the following:

A An IPv4 host address record. The A record is a forward lookup record that translates a host name into an IPv4 address.

AAAA An IPv6 host address record. The AAAA record is a forward lookup record that translates a host name into an IPv6 address.

CName A canonical name record. The CName record allows the use of more than one resource record to refer to a single host.

MX A Mail Exchanger record. The MX record identifies the email server for a domain. There can be multiple MX records for a domain, and they are used in order of precedence.

NS A Name Server record. The NS record identifies a name server for the domain. There can be multiple NS records in a domain.

PTR A pointer record. The PTR record is a reverse lookup record that translates an IP address into a host name. PTR records can be IPv4 or IPv6 addresses.

SOA A Start of Authority record. The SOA record is a version number record identifying the version number of the DNS zone.

SRV A Service record. The SRV record identifies the host name and port number of servers for the specified service.

All these resource records can be created or generated in the DNS Management console. They can also be created or generated by using Windows PowerShell, with the exception of the SOA record, which can’t be directly manipulated by Windows PowerShell. You can use the general Add-DnsServerResourceRecord or Set-DnsServerResourceRecord for all the resource records listed except the SOA record, plus there are specific Add cmdlets for the A, AAAA, CName, MX, and PTR records.

There are a wide variety of other DNS record types, but they are rarely of concern on typical Windows networks and they are not called out in the description for this objective, so they are unlikely to be on the exam.

The procedure for setting these record types is essentially the same for all except the SOA and NS records.

Creating A resource records

The A resource record is a host address record that points to an IPv4 address. DNS clients query the DNS server with a name, and if it matches an A record, the DNS server returns an IPv4 address. You can create an A record with either the DNS Manager console or by using the Add-DnsServerResourceRecordA or Add-DnsServerResourceRecord cmdlet.

In most DHCP-managed networks, the A record is usually automatically generated when the IPv4 address is handed out to the DHCP client. This is the preferred method for DHCP clients whose address is subject to change, but you can create a static A record by manually creating it. The problem with static records is that they need to be manually maintained if there are changes in the network. However, if there are servers with static IP addresses (as opposed to DHCP reservations), you might need to manually create the records.

To create an A record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the DNS domain name in which you want to create the record and select New Host (A Or AAAA).

4. Enter the host name in the Name box. (You don’t need to enter the FQDN, just the host name.)

5. Enter the IPv4 address in the IP Address box, as shown in Figure 3-15, and select Create Associated Pointer (PTR) Record if you’re using reverse lookup zones.

FIGURE 3-15 The New Host dialog box

6. Click Add Host to create the record.

To create the A record with Windows PowerShell, use the Add-DnsServerResourceRecordA cmdlet. For example:

Add-DnsServerResourceRecordA -ZoneName "TreyResearch.net" `
-Name trey-srv-14 `
-IPv4Address 192.168.10.14 `
-CreatePtr

You can also use the more general Add-DnsServerResourceRecord cmdlet to create the record. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-A `
-Name trey-srv-14 `
-IPv4Address 192.168.10.14 `
-CreatePtr

Both Windows PowerShell cmdlets create the exact same record and produce no output unless you include the -PassThru parameter. If you do include that, you see this:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
trey-srv-14 A 0 01:00:00 192.168.10.14

Creating AAAA resource records

The AAAA resource record is a host address record that points to an IPv6 address. DNS clients query the DNS server with a name, and the DNS server returns an IPv6 address if it matches an AAAA record. You can create an AAAA record with either the DNS Manager console or by using the Add-DnsServerResourceRecordAAAA or Add-DnsServerResourceRecord cmdlet.

In most DHCP-managed networks, the AAAA record is usually automatically generated when the IPv6 address is handed out to the DHCP client. This is the preferred method for DHCP clients whose address is subject to change, but you can create a static AAAA record by manually creating it. The problem with static records is that they need to be manually maintained if there are changes in the network. However, if there are servers with static IP addresses (as opposed to DHCP reservations), you might need to manually create the records.

To create an AAAA record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the DNS domain name in which you want to create the record and select New Host (A Or AAAA).

4. Enter the host name in the Name box. (You don’t need to enter the FQDN, just the host name. )

5. Enter the IPv6 address in the IP Address box, as shown in Figure 3-16, and select Create Associated Pointer (PTR) Record if you’re using reverse lookup zones.

FIGURE 3-16 New Host dialog box

6. Click Add Host to create the record.

7. Click OK to acknowledge the successful creation of the record and then click Done to exit out of the New Host dialog box.

To create the AAAA record with Windows PowerShell, use the Add-DnsServerResourceRecordAAAA cmdlet. For example:

Add-DnsServerResourceRecordAAAA -ZoneName "TreyResearch.net" `
-Name trey-srv-14 `
-IPv6Address 2001:db8::0e `
-CreatePtr

You can also use the more general Add-DnsServerResourceRecord cmdlet to create the record. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-AAAA `
-Name trey-srv-14 `
-IPv6Address 2001:db8::0e `
-CreatePtr

Both Windows PowerShell cmdlets create the exact same record and produce no output unless you include the -PassThru parameter. If you do include that, you see this:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
trey-srv-14 AAAA 0 01:00:00 2001:db8::e

Creating CNAME resource records

The CNAME resource record is a canonical record that adds an additional host name for a server. It is also called an Alias. The CNAME record points to a host name record and provides an alternative name for that host name. DNS clients query the DNS server with a name, and if it matches an CNAME record, the DNS server looks up the IP address for the host name that the CNAME points to and returns an IPv4 address for that host name. You can create a CNAME record with the DNS Manager console or by using the Add-DnsServerResourceRecordCName or Add-DnsServerResourceRecord cmdlet.

CNAME records are typically used to provide an alternate host name during a transition phase or to point to specific services that run on the same server. So, for example, you might use a CNAME of ns1 to point to trey-dc-02 in the treyresearch.net zone and also use a CNAME of ns1 to point to tail-dc-102 in the tailspintoys.com zone, enabling you maintain a uniform naming convention across domains.

To create a CNAME record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the DNS domain name in which you want to create the record and select New Alias (CNAME).

4. Enter the host name in the Name box. (You don’t need to enter the FQDN, just the host name.)

5. Enter the FQDN of the target host, as shown in Figure 3-17.

FIGURE 3-17 The New Resource Record dialog box

6. Click OK to create the record.

To create the CNAME record with Windows PowerShell, use the Add-DnsServerResourceRecordCName cmdlet. For example:

Add-DnsServerResourceRecordCNAME -ZoneName "TreyResearch.net" `
-Name dc1 `
-HostNameAlias trey-dc-02.treyresearch.net

You can also use the more general Add-DnsServerResourceRecord cmdlet to create the record. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-CName `
-Name dc1 `
-HostNameAlias trey-dc-02.treyresearch.net

Both Windows PowerShell cmdlets create the exact same record and produce no output unless you include the -PassThru parameter. If you do include that, you see this:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
dc1 CNAME 0 01:00:00 trey-dc-02.treyresearch.net.

Creating MX resource records

The MX resource record is a Mail Exchanger record that tells Simple Mail Transfer Protocol (SMTP) servers which host or hosts handle email for the domain. The MX record points to a host name record and includes a Mail Server Priority box that allows you to have backup mail servers with the email always being delivered to the mail server with the lowest value available. DNS clients query the DNS server for the MX record. If there is one or more, the DNS server returns the host names that the MX records point to, along with the priority for each server. You can create an MX record with the DNS Manager console or by using the Add-DnsServerResourceRecordMX or Add-DnsServerResourceRecord cmdlet.

To create an MX record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the DNS domain name in which you want to create the record and select New Mail Exchanger (MX).

4. Enter a Host Or Child Domain if appropriate. (In most environments, you can leave this box blank.)

5. Enter the FQDN of the mail server in the Fully Qualified Domain Name (FQDN) Of Mail Server box.

6. Enter the Mail Server Priority, as shown in Figure 3-18.

FIGURE 3-18 The New Resource Record dialog box for an MX Record

7. Click OK to create the record.

To create the MX record with Windows PowerShell, use the Add-DnsServerResourceRecordMX cmdlet. For example:

Add-DnsServerResourceRecordMX -ZoneName "TreyResearch.net" `
-Name "." `
-MailExchange trey-srv-12.treyresearch.net `
-Preference 10

You can also use the more general Add-DnsServerResourceRecord cmdlet to create the record. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-Name "." `
-MX
-MailExchange trey-srv-12.treyresearch.net `
-Preference 10

Both Windows PowerShell cmdlets create the exact same record and produce no output unless you include the -PassThru parameter. If you do include that, you see this:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
@ MX 0 01:00:00 [10][trey-srv-12.treyresearch.net.]

Creating PTR resource records

The PTR resource record is a pointer record that does a reverse lookup to point to a host name. DNS clients query the DNS server with an IP address. If it matches a PTR record, the DNS server returns the host name for that IP address. You can create a PTR record with the DNS Manager console or by using the Add-DnsServerResourceRecordPTR or Add-DnsServerResourceRecord cmdlet.

Reverse lookup zones are not required for most Windows networks, but when they are used, the PTR record is automatically generated when the IP address is handed out to the DHCP client or when the A or AAAA record is manually created. This is the preferred method, but you can create a static PTR record by manually creating it. The problem with static records is that they need to be manually maintained if there are changes in the network. However, if you don’t initially create a reverse lookup zone and then decide that you need one, you might well have servers with static addresses that need manually created records.

To create PTR record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Reverse Lookup Zones. For an IPv4 address in the 192.168.10/24 network, this is the 10.168.192.in-addr.arpa zone; for an IPv6 address in the 2001:db8::/64 network, the zone is the 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa zone.

3. Right-click the zone in which you want to create the record and select New Pointer (PTR).

4. Enter the IP address in the Host IP Address box. (You don’t need to enter the FQDN, just the IP address.)

5. Enter the FQDN in the Host Name box, as shown in Figure 3-19.

FIGURE 3-19 The New Resource Record dialog box for creating a PTR record

6. Click OK to create the record.

To create the PTR record with Windows PowerShell, use the Add-DnsServerResourceRecordPtr cmdlet. For example:

Add-DnsServerResourceRecordPtr -ZoneName 10.168.192.in-addr.arpa `
-Name "14" `
-PtrDomainName "trey-srv-14.treyresearch.net"

You can also use the more general Add-DnsServerResourceRecord cmdlet to create the record. For example:

Add-DnsServerResourceRecordPtr -ZoneName 10.168.192.in-addr.arpa `
-PTR
-Name "14" `
-PtrDomainName "trey-srv-14.treyresearch.net"

Both Windows PowerShell cmdlets create the exact same record, and produce no output unless you include the -PassThru parameter. If you do include that, you see the following:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
14 PTR 0 01:00:00 trey-srv-14.treyresearch.net.

Creating SRV resource records

The SRV resource record is a service location record that points to the location of key network resources. SRV records are required for AD DS domain controllers, but can also be required for other services. The necessary SRV records for domain controllers are created as part of the process of promoting a server to be a domain controller. Typically, _ldap and _kerberos SRV records are created in the _msdcs.<domainname> zone. The _kerberos record has a protocol of _tcp and a port number of 88, as shown in Figure 3-20.

FIGURE 3-20 The Properties dialog box for the _kerberos SRV record

The _ldap record is similar to the _kerberos record, except that it uses a port of 389. You usually should not modify these records, but it might be necessary to re-create them in the case of recovery from an unplanned event. Alternately, you might want to adjust the weight and priority of individual servers providing the service to manage load.

Other services that can use SRV records typically create their own records in DNS as part of their installation process, but you might have to manually create them as well. One other Microsoft service that uses SRV records is Microsoft Exchange, which uses SRV records to allow Outlook and other clients to autodiscover the Exchange server.

You can create an SRV record with the DNS Manager console or by using the Add-DnsServerResourceRecord cmdlet. To create an SRV record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server you on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the DNS domain name in which you want to create the record and select Other New Records.

4. Select Service Locator (SRV) from the list on the Resource Record Type dialog box, as shown in Figure 3-21, and click Create Record.

FIGURE 3-21 The Resource Record Type dialog box

5. Fill in the Service, Protocol, Priority, Weight, Port Number, and Host Offering This Service boxes on the New Resources Record dialog box, as shown in Figure 3-22.

FIGURE 3-22 The New Resource Record dialog box for a new SRV record

6. Click OK to create the record.

To create the SRV record with Windows PowerShell, use the Add-DnsServerResourceRecord cmdlet with the -SRV parameter set. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-Name _nntp._tcp `
-SRV `
-DomainName "trey-edge-1.treyresearch.net" `
-Port 119 `
-Priority 0 `
-Weight 0 `
-PassThru

The Windows PowerShell cmdlet doesn’t produce output unless you include the -PassThru parameter. If you do include it, you see the following:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
_nntp SRV 0 01:00:00 [0][0][113][trey-edge-1.treyresearch.net.]

Creating NS resource records

The NS resource record is a name server record that identifies a name server for the domain. You can create an NS record with the DNS Manager console or by using the Add-DnsServerResourceRecord cmdlet.

NS records are usually created automatically when servers are promoted to a domain controller, but you might have to manually create the NS record.

To create an NS record with the DNS Manager console, follow these steps:

1. Open the DNS Manager console.

2. Expand the server on which you want to create the record and then expand Forward Lookup Zones.

3. Right-click the Zone Name for the zone for which you want to create an NS record and select Properties from the menu.

4. Select the Name Servers tab and click Add to open the New Name Server Record dialog box shown in Figure 3-23.

FIGURE 3-23 The New Name Server Record dialog box

5. Enter FQDN of the new name server in the Server Fully Qualified Domain Name (FQDN) box and click the Resolve button.

6. Click OK and then OK again to create the record.

To create the NS record with Windows PowerShell, use the Add-DnsServerResourceRecord cmdlet. For example:

Add-DnsServerResourceRecord -ZoneName "TreyResearch.net" `
-NS `
-Name "." `
-NameServer trey-srv-12.treyresearch.net `
-PassThru

The Windows PowerShell cmdlet produces no output unless you include the -PassThru parameter. If you do include it, you see this:

HostName RecordType Timestamp TimeToLive RecordData
-------- ---------- --------- ---------- ----------
@ NS 0 01:00:00 trey-srv-12.treyresearch.net.