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Domain Name System

22: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6474966?start=0

What-is-DNS

Domain Name System

• Internet’s Phonebook
• Associates hosts with IP addresses
  • facebook.com = 31.13.69.228

Windows DNS

• Tools > DNS
• R-Click the server > All tasks
  • start
  • stop
• Forward Lookup Zones
• Reverse Lookup Zones
• Trust Points
  • All DNS servers to validate DNS data from other DNS servers
• Conditional Forwarders
  • Allow a DNS server to forward a specific DNS query to
    • another DNS server
    • several other DNS servers

The Host File

23: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6475302?start=0

C:\Windows\System32\drivers\etc\hosts

• To edit, you must open your text editor with administrative rights.
  • Start button > R-Click Notepad > Run as administrator
  • Drag the file into the editor (I didn’t know you could do this….)
• This file is commonly manipulated by hackers to redirect a browser to fake copies of known sites, such as facebook.com

DNS Zones

24: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6474970?start=0

• Contains DNS Resource Records
  • Records mapping Host names to IP addresses
• 2 Types of records
  • Forward lookup Zones
    • Host name to IP address
  • Reverse Lookup Zones
    • IP address to Host name

Primary DNS Zones

• Primary source of resource record information
• If not AD integrated, file stored at %windir%\system32\dns
• May be stored in AD if DNS server is also a writeable Domain Controller
  • This is good because it will then be replicated using AD replication
• Commonly used due to security and ease of use.
• These are the only zones that can be directly edited.

Purpose

• Allow DNS clients to resolve host name IP addresses

Secondary DNS Zones

• Replica of a primary DNS zone stored on a remote DNS server
• Required network connectivity of remote DNS server
• Is read-only.  Change requests are passed onto primary DNS server
• Are NOT saved in Active Directory

Purpose

• Redundancy
• Failover

Stub DNS Zones

• Read-only zone
• Information obtained from remote DNS server
• Only contains information about authoritative name servers
• No resource records for host names
• Can be saved in Active Directory

Purpose

• Less resource intensive version of a secondary zone.

Creating a DNS Zone

25: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6602196?start=0

Forward Lookup Zone

• Server Manager > Tools > DNS
• R-click Forward Lookup Zones > New Zone > New Zone Wizard
• Zone Type
  • Primary, Secondary or Stub
  • Store in AD?
    • If YES, a new window asking how to replicate
      • To all DNS servers running on domain controllers in this Forest
        • Broadest replication
      • To all DNS servers running on domain controllers in this Domain
        • Default
      • To all domain controllers in this domain
        • Just for Windows 2000 domain controllers (must be obsolete)
      • To all domain controllers specified in the scope of this directory partition
        • Needs to be configured before this option becomes available.
• Zone Name
  • A FQDN (MyOtherDomain.com)
  • A sub domain (the current domain is appended automatically)
• Dynamic Update
  • Allow only secure dynamic updates (recommended for Active Directory)
    • Default
    • Strongly advised unless there is a real need to do otherwise.
  • Allow both secure and non-secure dynamic updates
    • Allows updates from anywhere
    • Security Risk!  Untrusted sources can post updates!  BAD!
  • Do not allow dynamic updates
    • All records must be updated manually.
    • Typical in the non-windows world to my knowledge.
    • Only option available if NOT integrated with Active Directory

Reverse Lookup Zone

Almost the same as a forward, but subtle differences

• Server Manager > Tools > DNS
• R-click Reverse Lookup Zones > New Zone > New Zone Wizard
• Zone type, replication type – all the same as above
• Reverse Lookup Zone Name
  • IPv4 or IPv6
• Identify via
  • Network ID
    • First 3 octets of the subnet
      • Defines a subnet????
    • Auto populates Reverse Lookup Zone Name below
    • Example: 10.0.2
  • Reverse Lookup Zone Name
    • Example: 2.0.10.in-addr.arpa
• Dynamic Updates
  • Same as above

Resource Record Types

26: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6474972?start=0

Resource Records

• Provide DNS based data about computers on a network
  • Like a host name and its associated IP address
• SOA – Start of Authority
  • Every zone contains an SOA record
  • Contains information about the DNS server that provides the data for this zone (Master record?)
• NS – Name Server
  • Every zone has an NS record
  • Indicates the zone authoritative DNS server
• A – Address
  • Maps a FQDN to an IP address
  • mysub.mydomain.com > 10.0.2.10
• PTR – Pointer
  • Opposite of an A record
  • 10.0.2.10 > mysub.mydomain.com
• CNAME – Canonical Name
  • Creates and ‘alias’ for a FQDN
  • anothersub.mydomain.com > mysub.mydomain.com
• MX – Mail Exchange
  • List mail servers for the domain
  • Not listed, but Lower Priority values get HIGHER priority
    • Priority 0 = Highest priority
• SRV – Service Record
  • Specifies servers for a particular service
    • Add a PORT (?)
      • No example 🙁
    • _service._proto.name. TTL class SRV priority weight port target.
      • _sip._tcp.mysip.mydomain.com. 14400 IN SRV 0 5 5060 sipserver.mydomain.com.

Creating DNS Resource Records

27: https://www.udemy.com/windows-server-2016/learn/v4/t/lecture/6474968?start=0

• DNS > Server > Forward > Rclick zone name > Select record type
  • Selecting “Other new records” allows you to pick from a drop down list.
• Pretty straight forward from here.
  • For CNAMEs, you can ‘browse’ your local DNS for previously created records.
  • ALIAS records are NOT true alias records.  You cannot assign a ‘root’ domain “domain.com” to a CNAME.
    • Lame
• Reverse records create the rDNS
  • DNS > Server > Reverse Lookup > zone
    • Add the IP & a FQDN.
• Use NSLOOKUP to test the values
  • DNS > Rclick server > Launch nslookup
    • Very similar to dig
    • From cmd:
      • nslookup domain.name
      • nslookup ip.add.re.ss