1.5.10 DNS Records

You need to create a DNS record that identifies a service, protocol, and port number. Which record type would you create?

SRV Use an SRV (service) record to identify the service by protocol and port number. The A record identifies the hostname and IP address. A PTR record provides reverse lookup name resolution, providing the name from a given IP address. A CNAME record is an alias or alternate name for a host and points to an existing A record. An MX record identifies a mail server and identifies the FQDN of a mail server for a domain.

You are the network manager for the westsim.private domain. You are in the process of transitioning from IPv4 to IPv6 on your internal network. You want to configure DNS to provide hostname-to-IPv6 address and IPv6 address-to-hostname resolution for a specific IPv6-only host. Which record types would you create? (Select two.)

AAAA PTR Use an AAAA record to map a hostname to an IPv6 address. Use a PTR record to map an IPv6 address to a hostname. Use an A record to map a hostname to an IPv4 address. Use an SRV (service locator) record to identify servers that provide specific services, such as domain controllers. Use a CNAME record to create an alternate name for a host. Use an NS record to identify name servers that are authoritative for the zone.

You manage a network with Windows clients, multiple subnets, and Windows DNS servers. You want to be able to resolve a host name for a server on your network to its IPv4 address. What should you do?

Add an A record on the DNS server. The DNS server associates a host name with its IPv4 address using an A record. When a host name is used, the computer queries the DNS server and gets back the IP address that corresponds to the host name. The PTR record is used for reverse name resolution, where the client submits the IP address and gets the host name in response. The NS record identifies name servers that hold DNS records for a domain. The Lmhosts file is used for NetBIOS name resolution.

Your company has started the transition to IPv6. You need to configure records on the DNS server so that clients can submit a host name query and receive back an IPv6 address for the specified host. What should you do?

Create AAAA records The AAAA record maps an IPv6 (128-bit) DNS host name to an IP address. The A record maps an IPv4 (32-bit) DNS host name to an IP address. The PTR record maps an IP address to a host name. The NS resource record identifies all name servers that can perform name resolution for the zone.

You manage the intranet servers for EastSim Corporation. The company network has three domains: eastsim.com, asiapac.eastsim.com, and emea.eastsim.com. The main company website runs on the web1.eastsim.com server with a public IP address of 101.12.155.99. A host record for the server already exists in the eastsim.com zone. You want internet users to be able to use the URL http://www.eastsim.com to reach the website. What type of DNS record should you create?

CNAME Use a CNAME (alias) record to create alternate names for a host. The CNAME record points to the A (host) record. The CNAME record does not include the IP address of the host. Other DNS records are used as follows: Each host should be represented by a single A record. Use CNAME records to register additional (alternate) host names. Use a PTR record to provide IP address-to-host name resolution. Use an NS (name server) record to identify name servers that perform name resolution for the zone. Use an SOA (start of authority) record to identify zone information, such as the serial number. Use an SRV (service locator) record to identify servers that provide specific services, such as domain controllers.

Your company has started the transition to IPv6. You need to configure records on the DNS server so that clients can submit an IPv6 address and receive back the host name for that computer. What should you do?

Create PTR records. The PTR record maps an IP address to a host name. These records are often called reverse lookup records because they enable IP address-to-hostname resolution (instead of hostname-to-IP address resolution). The PTR record can be used for either IPv4 or IPv6 (IPv6 records are created in a different location on the DNS server). The AAAA record maps an IPv6 (128-bit) DNS host name to an IP address. The A record maps an IPv4 (32-bit) DNS host name to an IP address. The NS resource record identifies all name servers that can perform name resolution for the zone. There is no such thing as a PTR6 record.

Listed below are several DNS record types. Match the record type on the left with its function on the right.

Identify a domain controller. SRV Identify a mail server. MX Map a host name to an IPv4 address. A Map an IPv4 address to a host name. PTR Use DNS records as follows: Use an SRV (service locator) record to identify servers that provide specific services, such as domain controllers. Use an MX (mail exchange) record to identify e-mail servers. Use an A (host) record to map a host name to an IPv4 address. Use a PTR (pointer) record to map an IP address to a host name. Use a CNAME (alias) record to create alternate names for a host. The CNAME record points to the A (host) record. The CNAME record does not include the IP address of the host. Use a DNAME (domain name redirection) record to create an alias for the entire domain. Use an NS (name server) record to identify name servers that perform name resolution for the zone. Use an SOA (start of authority) record to identify zone information such as the serial number.

Listed below are several DNS record types. Match the record type on the left with its function on the right. (Record types may be used once or not at all.)

Identify a domain controller. SRV Identify a mail server. MX Map a host name to an IPv4 address. A Map an IPv4 address to a host name. PTR Use DNS records as follows: Use an SRV (service locator) record to identify servers that provide specific services, such as domain controllers. Use an MX (mail exchange) record to identify email servers. Use an A (host) record to map a host name to an IPv4 address. Use a PTR (pointer) record to map an IP address to a host name. Use a CNAME (alias) record to create alternate names for a host. The CNAME record points to the A (host) record. The CNAME record does not include the IP address of the host. Use a DNAME (domain name redirection) record to create an alias for the entire domain. Use an NS (name server) record to identify name servers that perform name resolution for the zone. Use an SOA (start of authority) record to identify zone information such as the serial number.

Mary is in charge of DNS administration for her network. The private network consists of a single Active Directory domain called private.westsim.com. DNS data is stored in an Active Directory-integrated zone. The sales department has just installed a web server called SalesWeb. This server will host an intranet site for use by the sales team. They want this server to be accessible using the URL sales.westsim.com. What should Mary do?

In the westsim.com domain, create a CNAME record called Sales. Identify SalesWeb.private.westsim.com as the target. Use a CNAME record to provide an alternate, or alias, URL for a specific host if the URL points to a host that is not within the same domain.

Emma is a systems administrator for WestSim Corporation. The network has multiple domains with DNS and DHCP services configured in each domain. All servers are running Windows Server 2016, and all clients are running Windows 10. All hosts are members of the acct.westsim.com domain. This domain's records are stored in a primary zone. As part of a new security initiative, the IT department has developed a custom application that reports the hostname of each client that tries to access three sensitive servers in the accounting department. Emma has been asked to test the new application. During a random test, she finds that the program is not reporting the host names for some clients, even though it properly records their IP addresses. Emma realizes that the custom application submits reverse lookup requests to the DNS server to discover the host name for the specified IP address. She also realizes that the clients whose host names could not be notified have manually-configured static IP addresses on the 192.168.3.0 subnet using a default subnet mask. What should Emma do?

Manually create a PTR record in the 3.168.192.in-addr.arpa zone for each host. In this example, the custom application cannot determine the host name for a given host because of a missing PTR record in the 3.168.192.in-addr.arpa reverse lookup zone. The application can find these records for other hosts because the DHCP server automatically creates the record when the IP address is assigned. Each of these hosts has a manually configured IP address, so the corresponding PTR records are not being created automatically.

Your organization's IT department has developed a custom application that reports the hostname of each client that tries to access three servers in the accounting department that store sensitive information. You do a random test and find that the program is not reporting the host names for some clients even though it properly records their IP addresses. This is because the custom application submits reverse lookup requests to the DNS server to discover the host names for the specified IP addresses. As you investigate further, you learn that the clients whose hostnames could not be reported have static IP addresses and are on subnet 192.168.3.0. What should you do?

Manually create a PTR record in the 3.168.192.in-addr.arpa zone for each host. In this example, the custom application cannot determine the hostname for a given host because of a missing PTR record in the 3.168.192.in-addr.arpa reverse lookup zone. The application can find these records for other hosts because the DHCP server automatically creates the record when the IP address is assigned. Each of these hosts has a manually configured IP address, so the corresponding PTR records are not being created automatically.

Listed below are several DNS record types. Match the record type on the left with its function on the right.

Points a hostname to an IPv4 address. A Provides alternate names to hosts that already have a host record. CNAME Points an IP address to a hostname. PTR Points a hostname to an IPv6 address. AAAA Identifies servers that can be used to deliver mail. MX Records are used to store entries for hostnames, IP addresses, and other information in the zone database. Below are some common DNS record types: The A record maps an IPv4 (32-bit) DNS hostname to an IP address. This is the most common resource record type. The AAAA record maps an IPv6 (128-bit) DNS hostname to an IP address. The PTR record maps an IP address to a hostname (it points to an A record). The MX record identifies servers that can be used to deliver email. The CNAME record provides alternate names (or aliases) to hosts that already have a host record. Using a single A record with multiple CNAME records means that when the IP address changes, only the A record needs to be modified.

You are the manager for the westsim.com domain. All computers are members of the westsim.com domain. A single Windows Server 2016 server is the domain controller and DNS server for the domain. You have recently installed a new server, srv12, with the IP address 192.168.3.199/24. You need to manually create a record in the DNS database that provides IP address-to-hostname resolution. Which command would you use?

dnscmd /recordadd 3.168.192.in-addr.arpa 199 PTR srv12.westsim.com To add a DNS record, use the following format: dnscmd /recordadd zonename recordname recordtype recorddata To provide IP address-to-hostname resolution, create a PTR record. For the zone name, reverse the octets in the subnet address and add in-addr.arpa. For the record name, use the last octet in the IP address. For the record data, use the FQDN for the host.