Domain Name System
Domain Name System
• Domain Name System (DNS) Terms
• DNS components
• Troubleshooting DNS
• DNS FAQ
• Hostname—name of the computer. No more than 255
characters. Equivalent to the computers first name.
• Host File—text file that lists hostnames to IP addresses
• Namespace—name of the domain, not specifically and Active
Directory Domain. This is equivalent to the computers last
• Fully qualified domain name (FQDN)—first name and last
• Name server—DNS server that will resolve FQDN’s to IP
• recursion—server directed process to resolve a FQDN. If the server
cannot resolve it with it’s own information, it will ask an upstream
server. The recursion process starts at the root servers for the .com
and works down through the top level domain servers. The process is
1. Client requests a name like www.facebook.com
2. DNS server asks the root servers for the .com domain name servers.
3. Root servers give a list of servers for the .com domain.
4. DNS servers query the .com nam servers for facebook.com
5. It then queries the provided name servers for the
6. Finally, the DNS server provides the IP address
7. DNS server passes the IP address to the client.
8. The client uses the IP to connect to the web server for
• Forwarding—alternative to recursion.
Lateral request to another name server
within the network.
• Service resource records (SRVs)—a
record within a DNS namespace to
resolve a service to a hostname.
Essential to Active Directory.
• Dynamic DNS(DDNS) update—allows
DNS client to register their hostnames
in an assigned namespace.
• Fowarders—DNS servers to
which the DNS server will
refer queries when it cannot
resolve them itself. Using
forwarders prevents this
server from using recursion
to resolve DNS queries. You
can use forwarders for
quicker name resolution.
Typically can configure to
point to your ISP’s DNS
• Root Hints—servers to be used for root hints when forwarders
are not configured or do not respond. Lists 13 root hint
servers on the Internet. You can add your own servers.
• Forward Lookup Zones—resolves hostnames to IP addresses. Contains
the host records for the configured zone. There are three types of zones:
• Standard Primaryis a text file in which the server maintains the records for
a given namespace.
• Standard Secondaryread-only copy of primary or AD zone.
• AD IntegratedDNS records are stored in the AD Database and replicated
between DC’s, not zone transfers.
• Reverse Lookup Zone—resolves IP addresses to host names.
Also used to provide a level of security with DNS reverse
• Service Resource/Locator Records (SRV)—contains Active Directory
related information, such as authentication services.
• _gcLDAP service to look up data within the global catalog
• _kerberosThe authentication process
• _kpasswdanother part of authentication process
• _ldapLDAP service to look up data within the domain
• Event loggingevent log created for the DNS role
• MonitoringMonitoring tab in DNS server properties which allows
you to do simple pass/fail tests and recursive tests
• NSLookupcan query your own server or remotes domain names.
• DNScmdcommand-line tool that can perform most tasks in the
GUI as well as troubleshooting tasks.
• Dnscmd /infoconfiguration of the DNS server
• Dnscmd /clearcache empties stale, unresolved records
• Net viewuses netBIOS to retrieve info about a host
• Nbtstatuses the netBIOS table to view information about a host or
• PINGtest connectivity by IP address AND by hostname.
• Dcdiagfirst choice to perform a quick health check on the DNS