Your network contains an Active Directory domain named contoso.com. The network contains a member server named Server1 that runs Windows Server 2012 R2. Server1 has the DNS Server server role installed and has a primary zone for contoso.com.
The Active Directory domain contains 500 client computers. There are an additional 20 computers in a workgroup.
You discover that every client computer on the network can add its record to the contoso.com zone.
You need to ensure that only the client computers in the Active Directory domain can register records in the contoso.com zone.
What should you do first?
A. Move the contoso.com zone to a domain controller that is configured as a DNS server.
B. Configure the Dynamic updates settings of the contoso.com zone.
C. Sign the contoso.com zone by using DNSSEC
D. Configure the Security settings of the contoso.com zone.
Correct Answer: A
Explanation/Reference:
Explanation:
If you install DNS server on a non-DC, then you are not able to create AD-integrated zones. DNS update security is available only for zones that are integrated into AD DS. When your directory- integrate a zone, access control list (ACL) editing features are available in DNS Manager so that you can add or remove users or groups from the ACL for a specified zone or resource record.
• Active Directory’s DNS Domain Name is NOT a single label name (“DOMAIN” vs. the minimal requirement of “domain.com.” “domain.local”, etc.).
• The Primary DNS Suffix MUST match the zone name that is allowing updates. Otherwise the client doesn’t know what zone name to register in. You can also have a different Connection Specific Suffix in addition to the Primary DNS Suffix to register into that zone as well.
• AD/DNS zone MUST be configured to allow dynamic updates, whether Secure or Secure and Non-Secure. For client machines, if a client is not joined to the domain, and the zone is set to Secure, it will not register either.
• You must ONLY use the DNS servers that host a copy of the AD zone name or have a reference to get to them. Do not use your ISP’s, an external DNS address, your router as a DNS address, or any other DNS that does not have a copy of the AD zone. Internet resolution for your machines will be accomplished by the Root servers (Root Hints), however it’s recommended to configure a forwarder for efficient Internet resolution.
• The domain controller is multihomed (which means it has more than one unteamed, active NIC, more than one IP address, and/or RRAS is installed on the
• The DNS addresses configured in the client’s IP properties must ONLY reference the DNS server(s) hosting the AD zone you want to update in. This means that you must NOT use an external DNS in any machine’s IP property in an AD environment. You can’t mix them either. That’s because of the way the DNS Client side resolver service works. Even if you mix up internal DNS and ISP’s DNS addresses, the resolver algorithm can still have trouble asking the correct DNS server. It will ask the first one first. If it doesn’t get a response, it removes the first one from the eligible resolvers list and goes to the next in the list. It will not go back to the first one unless you restart the machine, restart the DNS Client service, or set a registry entry to cut the query TTL to 0. The rule is to ONLY use your internal DNS server(s) and configure a forwarder to your ISP’s DNS for efficient Internet resolution.
This is the reg entry to cut the query to 0 TTL:
The DNS Client service does not revert to using the first server. The Windows 2000 Domain Name System (DNS) Client service (DNS cache) follows a certain algorithm when it decides the order in which to use the DNS servers.
• For DHCP clients, DHCP Option 006 for the clients are set to the same DNS server.
• 8.If using DHCP, DHCP server must only be referencing the same exact DNS server(s) in its own IP properties in order for it to ‘force’ (if you set that setting) registration into DNS. Otherwise, how would it know which DNS to send the reg data to?
If the AD DNS Domain name is a single label name, such as “EXAMPLE”, and not the proper format of “example.com” and/or any child of that format, such as “child1.example.com”, then we have a real big problem.
DNS will not allow registration into a single labeldomain name.
This is for two reasons:
It’s not the proper hierarchal format. DNS is hierarchal, but a single label name has no hierarchy. It’s just a single name.
Registration attempts cause major Internet queries to the Root servers. Why? Because it thinks the single label name, such as “EXAMPLE”, is a TLD (Top Level Domain), such as “com”, “net”, etc. It will now try to find what Root name server out there handles that TLD. In the end it comes back to itself and then attempts to register. Unfortunately, it does NOT ask itself first for the mere reason it thinks it’s a TLD. (Quoted from Alan Woods, Microsoft, 2004):
“Due to this excessive Root query traffic, which ISC found from a study that discovered Microsoft DNS servers are causing excessive traffic because of single label names, Microsoft, being an internet friendly neighbor and wanting to stop this problem for their neighbors, stopped the ability to register into DNS with Windows 2000SP4, XP SP1, (especially XP, which cause lookup problems too), and Windows 2003. After all, DNS is hierarchal, so therefore why even allow single label DNS domain names?” The above also *especially* applies to Windows Vista, 7, 2008, 2008 R2, and newer.
‘Register this connection’s address” on the client is not enabled under the NIC’s IP properties, DNS tab.
Maybe there’s a GPO set to force Secure updates and the machine isn’t a joined member of the domain.
ON 2000, 2003 and XP, the “DHCP client” Service not running. In 2008/Vista and newer, it’s the DNS Client Service. This is a requirement for DNS registration and DNS resolution even if the client is not actually using DHCP.
You can also configure DHCP to force register clients for you, as well as keep the DNS zone clean of old or duplicate entries. Seethe link I posted in my previous post.
