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74 Cards in this Set

  • Front
  • Back
What is DNS?
The Domain Name System (DNS) is a hierarchical, distributed database that maps logical host names to IP addresses
What does a DNS server hold?
A DNS server holds a database of hostnames and their corresponding IP addresses. Clients query the DNS server to get the IP address of a given host.
What was used before DNS?
a hosts file saved on each host computer
What makes up the DNS hierarchy?
The DNS hierarchy is made up of the following components:
- . (dot) domain (also called the root domain)
- Top Level Domains (TLDs) (.com, .edu, .gov)
- Second-level and additional domains
- Hosts
What is a FQDN?
Fully Qualified Domain Name - includes the host name and the name of all domains back to root.
What makes DNS a distributed database?
DNS is a distributed database because no one server holds all of the DNS information. Instead, multiple servers hold portions of the data.
What is a zone?
Zones typically contain one or more domains, although additional servers might hold information for child domains.
What do DNS servers do?
DNS servers hold zone files and process name resolution requests from client systems.
What is a DNS forward lookup?
A forward lookup uses the host name (or the FQDN) to find the IP address
What is a DNS reverse lookup?
A reverse lookup uses the IP address to find the host name (or FQDN).
What is an A record?
The A record maps a host name to an IP address and is used for forward lookups.
What is a PRT record?
The PTR record maps an IP address to a host name and is used for reverse lookups.
What is a CNAME record?
The CNAME record provides an alternate name (an alias) for a host.
What is a SRV record?
The SRV record identifies a service, such as an Active Directory domain controller.
How are DNS records created?
Manually, or dynamically using Dynamic DNS (DDNS). With DDNS, hosts automatically register and update their corresponding records with the DNS server.
What is the process followed when a client computer needs to find an IP address?
- The client examines its HOSTS file for the IP address.
- If the IP address is not in the HOSTS file, it examines its local DNS cache for the IP address.
- If the IP address is not in the cache, the client sends the request to a DNS server.
What is the process when a DNS server received a name resolution request?
1) The DNS server examines its local DNS cache for the IP address
2) If the IP address is not in the server cache, it checks its HOSTS file.
3) If the information is not in the HOSTS file, the server checks any zones for which it is authoritative.
4) Forwarding or Recursion
5) After the information is found or received from another server, the DNS server returns the result to the client, and places the information in its server cache.
What is an authoritative DNS server?
a DNS server that has a full, complete copy of all the records for a particular zone.
What is DNS Forwarding?
Where the DNS server forwards the name resolution request to another DNS server, then waits for a response from that server
What is DNS Recursion
Where the DNS server queries root domain servers, top-level domain server and other DNS servers in an iterative manner until it finds the one that hosts the target domain.
What is a caching-only DNS server?
A caching-only DNS server has no zone information; it is not authoritative for any domains. It uses information in its server cache, or forwarding or recursion, to respond to client queries.
Who can install DNS in Server 2008?
Members of the Domain Admins group
Which versions of server 2008 can have DNS installed on them?
You can install DNS on any version of Windows Server 2008 except for the Windows Server 2008 Web Server edition.
What type of IP address must the DNS server have?
Static
How would you add the DNS role from a command prompt (or on a server core)?
start /w ocsetup DNS-Server-Core-Role
What command will give a list of installed services on a server?
Run the oclist command to get a list of services (including DNS) installed on a server.
What can be used to manage DNS on Server 2008?
Use the DNS snap-in or the dnscmd command to manage DNS.
What is a primary DNS zone?
the master copy of a zone database
What are the properties of a primary zone?
- The primary zone is the only writeable copy of the zone database.
- Changes to the zone can only be made to the primary zone.
- The server that holds the primary zone is called a primary server.
- Each zone can have only a single primary zone server.
- Zone data is stored in a text file.
What is a secondary DNS zone?
A secondary zone is a read-only copy of the zone database.
What are the properties of a secondary DNS zone?
- Changes cannot be made to the records in a secondary zone.
- A server that holds a secondary zone is called a secondary server.
- Secondary servers copy zone data from other servers through a process called zone transfer.
- Secondary servers can copy zone data from the primary server or other secondary servers.
- Zone data is stored in a text file.
What is an Active Directory-integrated DNS zone?
An Active Directory-integrated zone holds zone data in Active Directory instead of a text file.
What are the properties of an Active Directory-integrated DNS zone?
- Active Directory-integrated zones are multi-master zones, meaning that changes to the zone information can be made by multiple servers. Multiple servers hold read-write copies of the zone data.
- Only DNS servers that are domain controllers can host Active Directory-integrated zones.
- Storing zone data in Active Directory provides automatic replication, fault tolerance, and distributed administration of DNS data.
- Replication of zone data occurs during Active Directory replication and is secured by Kerberos.
What is a stub zone?
A stub zone is a zone with only a partial copy of the zone database.
What are the properties of a stub zone?
- The stub zone only contains information about the name servers that are authoritative for the zone; it does not contain information for other hosts.
- A stub zone is not authoritative for the zone; its purpose is to identify the name servers that can be contacted for full zone information.
- The stub zone is dynamic, meaning that it will keep the list of name servers for the zone updated automatically.
- Use a stub zone to forward name requests based on zones while keeping name server lists updated automatically.
What is the GlobalNames DNS zone?
The GlobalNames zone is a special zone in the DNS database that is used for single-label name resolution.
What is a GlobalNames DNS zone used for?
- Allow clients to use simple host names without domain information for name resolution. For example, to contact a server named web1.corp.us.westsim.private, users could simply enter the single-label name web1.
- Allow DNS clients to contact NetBIOS-only hosts without the need for a WINS server.
- Allow IPv6-only hosts to contact NetBIOS hosts (IPv6 does not support the use of WINS).
What are the features of a GlobalNames zone?
- When users enter a single-label name, the client computer first tries to resolve the name using DNS and the search suffix configuration. If that process fails, the GlobalNames zone is checked (if it exists).
- Using the GlobalNames zone does not require any changes to client machines.
- Dynamic updates are not supported on the GlobalNames zone. You must manually create each record in the GlobalNames zone.
- Use the GlobalNames zone to replace WINS servers on your network only when you have a small number of hosts that do not support DNS. For a large number of NetBIOS-only hosts, or to support dynamic registration of single-label names, continue to use a WINS server.
What is a forward lookup DNS zone?
A forward lookup zone provides hostname-to-IP address resolution. Clients query the DNS server with the hostname, and receive the IP address in return.
What is a reverse lookup DNS zone?
A reverse lookup zone provides IP address-to-hostname resolution. Clients query the DNS server with the IP address, and receive the hostname in return.
How many servers can hold the primary zone file?
Only one server can hold the primary zone file. To place zone data on multiple servers, configure secondary servers.
Where does Windows store standard zone data?
Windows stores standard zone data in the %windir%\System32\Dns directory. The file is a text file with .dns added to the zone name.
Which types of zone support dynamic updates?
Primary and Active Directory-integrated zones support dynamic updates. Use an Active Directory-integrated zone to use secure dynamic updates.
What types of record does a reverse lookup zone hold?
Reverse lookup zones hold PTR (pointer) records. The PTR record maps the IP address to an A record.
What type of zones can a reverse lookup zone be?
A reverse lookup zone can be a primary zone, a secondary zone, or an Active Directory integrated zone.
What is the SOA (Start of Authority) record?
The first record in any DNS database file is the SOA. It defines the general parameters for the DNS zone, and it is assigned to the DNS server hosting the primary copy of a zone. There is only one SOA record, and it is the first record in the zone database file. The SOA record includes parameters such as the authoritative server and the zone file serial number.
What is an NS (Name Server) record?
The NS resource record identifies all name servers that can perform name resolution for the zone. Typically, there is an entry for the primary server and all secondary servers for the zone (all authoritative DNS servers).
What is an A (Host Address) record?
The A record maps an IPv4 (32-bit) DNS host name to an IP address. This is the most common resource record type.
What is an AAAA (Quad A) record?
The AAAA record maps an IPv6 (128-bit) DNS host name to an IP address.
What is an MX (Mail Exchanger) Record?
The MX record identifies servers that can be used to deliver e-mail.
What is a CNAME record?
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 one A record needs to be modified.
What is a DNAME record?
The DNAME record provides alternate names (or aliases) to domains that already have a host record.
What is a SRV (Service Locator) record?
The SRV record is used by Windows Server 2008 to register network services. This allows clients to find services (such as domain controllers) through DNS. Windows 2008 automatically creates these records as needed and during domain controller installation.
What is a PTR (Pointer) record?
In a reverse lookup zone, the PTR record maps an IP address to a host name (i.e. "points" to an A record). Where IPv4 PTR records are created in the in-addr.arpa namespace, reverse lookup zones for IPv6 addresses should be created in the ip6.arpa namespace.
What are WINS and WINS-R records?
Add these records to a zone when you want to allow DNS to use WINS resolution. The WINS resource record allows DNS queries that fail to resolve to be forwarded to the WINS servers in the WINS resource record. The WINS-R resource record allows the resolution of a reverse query that is not resolvable through DNS.
How can DNS records be automatically created on a DNS server?
By using Dynamic DNS. Dynamic DNS is required to support Active Directory.
When do dynamic updates occur?
- A network connection's IP address is added, deleted, or changed.
- The DHCP server changes or renews an IP address lease.
- The client's DNS information is manually changed using ipconfig /registerdns.
- The client boots.
- A server is promoted to a domain controller.
Which Windows clients support DDNS?
Windows clients (2000 and above) create their A records with the DNS server. Windows 9x/Me/NT clients do not support dynamic DNS.
How does the DHCP server tie in with DDNS?
The DHCP server registers the PTR record with the DNS server for clients capable of dynamic updates. The DHCP server updates both the A and PTR records for clients that do not support dynamic updates.
Are dynamic updates enabled by default on a primary zone?
Dynamic updates are not enabled on primary zones. You can enable dynamic updates when you create the zone or modify the zone properties later to enable this feature.
Are dynamic updates enabled by default on an Active Directory-integrated zone?
Dynamic updates are enabled on Active Directory-integrated zones. Note: When you convert a primary zone to an Active Directory-integrated zone, the current dynamic update setting is retained.
What are secure dynamic updates?
With secure dynamic updates, only domain members can create records, and only the original client can modify or remove records.
What is used to keep track of changes to a DNS zone?
The zone serial number keeps track of changes to the zone. When you make changes to the zone, the serial number is incremented.
What is a DNS master server?
A master server is the server from which the secondary copies the zone data. The master server can be the primary server or another secondary server.
What are the two types of zone transfer?
Zone transfers can copy all records or only changed records:
- A full zone transfer (AXFR) copies all of the zone data with each zone transfer.
- A partial (or incremental) zone transfer (IXFR) copies only the changed records. This is the default method on Windows Server 2008.
Are zone transfers enabled in Server 2008 by default?
By default, zone transfer in Windows Server 2008 is disabled for security reasons. To use zone transfers, manually enable the feature in the DNS settings in Server Manager.
How can you restrict the servers to which zone transfers are allowed?
- Allow zone transfers only to servers that are listed as name servers.
- Allow zone transfers only to servers you specifically identify.
How does a secondary server initiate a zone transfer?
- The secondary server contacts the master server and compares the serial number on the master with the serial number in its copy.
- If the serial number on the master is greater, the secondary initiates zone transfer.
- If the serial number is the same (or lower) on the master, no zone transfer takes place.
What is DNS notify?
Windows DNS servers support the use of DNS Notify. With DNS Notify, master servers are configured with a list of slave DNS servers.
How does DNS notify work?
- When a change takes place, the master notifies the slave servers that the zone has changed.
- The secondary server then initiates zone transfer, first checking the serial number, then requesting changes.
What is a DNS caching server?
A caching only server runs DNS but has no zones configured. Use a caching only server to improve performance while eliminating zone transfers.
How does an Active Directory-integrated zone store DNS information?
An Active Directory-integrated zone stores DNS information in Active Directory rather than in a zone file. Zone information is copied automatically when Active Directory replicates.
How can you secure zone transfers to secondary servers?
Active Directory replication traffic is automatically secured. To secure zone transfers to secondary servers, use IPsec between servers.
How can you force an update of DNS zone data?
You can force an update of zone data through the DNS console or by using the Dnscmd command