CN2140 Server II Kemtis Kunanuraksapong MSIS with Distinction MCT, MCITP, MCTS, MCDST, MCP, A+

Agenda Chapter 4: Configuring and Managing the DNS Server Role Exercise Lab Quiz

HOST file Text files that were stored locally on each computer The HOSTS file listed each name of the host and its corresponding IP address Whenever a new host was added to the network, an administrator would manually update the HOSTS file with the new host name or IP address information

Benefits of Domain Name System Scalability Constancy ▫Host name remain the same regardless of IP assigned Ease of Use Simplicity

DNS Namespaces A DNS namespace is a hierarchical, tree- structured list of DNS host names ▫An unnamed root that is used for all DNS operations ▫Each domain can have additional child domains See Figure 4-1 on Page 59

DNS Namespaces The DNS namespace has a hierarchical structure and each DNS domain name is unique within a namespace. At the top of the Internet DNS namespace is the root domain. ▫The root domain is represented by “.” (a period).

DNS Namespaces (Cont.) Under the DNS root domain, the top-level domains, or first-level domains, are organizational types such as.org,.com, and.edu ▫Generic  generic, top-level domain names  See Table 401 on Page 60 ▫Country code  Examples of country code domain names are.uk,.jp ▫Infrastructure domain .arpa is the Internet’s infrastructure domain name.

DNS Namespaces (Cont.) Second-level domains are registered to individuals or organizations Second-level DNS domains can have many subdomains and any domain can have hosts

Fully Qualified Domain Name (FQDN) DNS uses the fully qualified domain name (FQDN) to map a host name to an IP address An FQDN describes the exact relationship between a host and its DNS domain

DNS Server Types DNS server types are determined by the type of zone or zones they host and by the functions they perform ▫Primary Name Server ▫Secondary Name Server  Retrieve the records from zone transfer for secondary zone ▫Caching-only Server  The server doesn’t host any zones A DNS server may host either primary or secondary zones or both A server is said to be authoritative if it hosts a primary or secondary zone for a DNS domain

AD-Integrated Zones Zones are stored in Active Directory. No distinction between primary and secondary servers. Changes made on one DNS server are replicated to other DNS Server.

Zones A zone is a collection of host name–to–IP address mappings for hosts in a contiguous portion of the DNS namespace Zone data is maintained on a DNS name server and is stored in one of two ways: ▫standard zone or a file-backed zone  As a text-based zone file containing lists of mappings ▫Active Directory–integrated zone  Within an Active Directory database

Standard Primary Zone A standard primary zone hosts a read/write copy of the DNS zone in which resource records are created and managed ▫Only one server can host and load the master copy of the zone ▫Only the server hosting the primary zone is allowed to accept dynamic updates and process zone changes

Standard Secondary Zone A copy of the zone file may be stored on one or more servers to balance network load, provide fault tolerance, or avoid forcing queries across a slow, wide area network (WAN) link A read-only copy of the standard primary zone Information from a primary zone is transmitted to a secondary zone by performing a zone transfer

Zone Transfers Full zone transfer (AXFR) ▫The entire contents of the zone is copied from the primary server to the secondary server during each zone transfer Incremental zone transfer (IXFR) ▫Only changed information is transmitted after an initial AXFR

Forward Lookup Zone Most queries sent to a DNS server are forward queries ▫They request an IP address based on a DNS name ▫Includes Host (A) resource records that translate form host name to IP address

Reverse Lookup Zone The Reverse Lookup zone is in-addr.arpa domain Enables a host to determine another host’s name based on its IP address ▫Contains the Pointer (PTR) resource record that translates from IP addresses to host names

Stub Zone A copy of a zone that contains only those resource records necessary to identify the authoritative DNS servers for that zone A stub zone is a pointer to the DNS server that is authoritative for that zone The stub zone contains a subset of zone data consisting of an SOA, an NS, and an A record Resource records in the stub zone cannot be modified

Resource Records The resource record is the fundamental data storage unit in all DNS servers ▫Start of Authority (SOA) ▫Name Server (NS) ▫Host (A) ▫Host (AAAA) ▫Canonical Name (CNAME) ▫Mail Exchanger (MX) ▫Pointer (PTR) ▫Service Record (SRV)

Start of Authority (SOA) Resource Records Identifies which name server is the authoritative source of information for data ▫The first record in the zone database file must be an SOA record ▫In the Windows Server 2008 DNS server, SOA records are created automatically with default values when you create a new zone

Name Server (NS) Resource Records The server that can provide an authoritative name-to-IP address mapping for a zone or domain

A and AAAA Resource Records A record ▫Use to translate the host name to the IPv4 address AAAA record ▫Use to translate the host name to the IPv6 address The Pointer (PTR) record ▫Provide an IP address-to-name mapping, which is found in the reverse lookup zones.

Canonical Name (CNAME) Resource Record Alias record, is used to specify an alternative name for the system specified in the Name field

Mail Exchanger (MX) Resource Records Identifies the servers for a domain The preference value defines which mail server to use first ▫If you get an error that it cannot contact RPC server  SRV records are missing  DNS is not configured properly  You are not pointing to the correct DNS server

Service Record (SRV) Enables clients to locate servers that are providing a particular service. ▫Windows Server 2008 Active Directory clients rely on the SRV record to locate the domain controllers they need to validate logon requests

Root Hints The DNS Server service must be configured with root hints to resolve queries ▫For names that it is not authoritative for ▫For which it contains no delegations Root hints contain the names and IP addresses of the DNS servers authoritative for the root zone ▫You can use the DNS console to manage the list of root servers, as well as the dnscmd command-line utility

Root Hints By default, DNS servers use a root hints file, called cache.dns, on Microsoft DNS servers ▫%systemroot%\System32\Dns folder on the server computer. When the server starts, cache.dns is preloaded into server memory By using root hints to find root servers, a DNS server is able to complete recursive queries

DNS Queries Iterative DNS Queries ▫See Figure 4-4 on Page 83 Recursive DNS Queeries ▫See Figure 4-5 on Page 84

DNS Resolver Cache Any Windows computer, key the following at a command prompt: ▫ipconfig /displaydns: To purge the cache, key the following at a command prompt: ▫ipconfig /flushdns:

Forwarders A forwarder is a DNS server on a network used to forward DNS queries for external DNS names to DNS servers outside of that network A conditional forwarder forwards queries on the basis of domain name

Troubleshooting DNS and the Name Resolution Process DNS MMC Nslookup Logging features Dnscmd

Nslookup

Dnscmd Command Can be used to: ▫Script batch files ▫Help automate the management and updates of existing DNS server configurations ▫Perform setup and configuration of DNS servers

Advanced DNS Server Properties Advanced DNS server properties refer to the settings that can be configured in the Advanced tab of the DNS Server Properties dialog box These properties relate to server-specific features, such as ▫Disabling recursion ▫Handling resolution of multi-homed hosts ▫Achieving compatibility with non-Microsoft DNS servers

Assignment Summarize the chapter in your own word ▫At least 75 words ▫Due BEFORE class start on Thursday Lab 4 ▫Due BEFORE class start on Monday