Domain Name System (DNS)

Network Service -*What Is a Domain Namespace?Root DomainSubdomainsSecond-Level DomainTop-Level DomainFQDN:server1.sales.south.nwtraders.comsouthnwtraderscomsaleswesteastorgnetHost: server1

Network Service -*Standards for DNS NamingThe following characters are valid for DNS names:

A-Za-z 0-9 Hyphen (-)

The underscore (_) is a reserved character

Network Service -*What Are the Components of a DNS Solution?

Network Service -*What Is a DNS Query?DNS clients and DNS servers both initiate queries for name resolutionAn authoritative DNS server for the namespace of the query will either:Check the cache, check the zone, and return the requested IP addressReturn an authoritative, NoA non-authoritative DNS server for the namespace of the query will either:Forward the unresolvable query to a specific query server called a ForwarderUse root hints to locate an answer for the query DNS server name resolution DNS Query Recursive() iterative() Query 2 .

Network Service -*How Recursive Queries Work Recursive() Query DNS client Local DNS Server Query Query Query Query Query .DNS server checks the forward lookup zone and cache for an answer to the queryDatabaseLocal DNS Server

Network Service -*How Root Hint WorksRoot hints Local DNS Server Query IP addresses Local DNS Server DNS root servers Query .microsoftCluster ofDNS ServersRoot HintsDNS ServerCluster of Root (.) ServerscomComputer1

Network Service -*How Iterative Queries WorkIterative() Query Root server . . DNS server Query .Computer1Local DNS Servernwtraders.comRoot Hint (.).comRecursive query for mail1.nwtraders.com172.16.64.11Iterative QueryIterative QueryIterative QueryAsk .comAsk nwtraders.comAuthoritative Response321

Network Service -*How Forwarders WorkForwarder() DNS(Domain Name System) DNS DNS Forward() DNS . Computer1nwtraders.comRoot Hint (.).comIterative QueryIterative QueryIterative QueryAsk .comAsk nwtraders.comAuthoritative ResponseLocal DNS ServerForwarderRecursive query for mail1.nwtraders.com172.16.64.11172.16.64.11Recursive Query

Network Service -*How DNS Server Caching WorksCaching .Wheres Client A?Client1Client2ClientAClientA is at 192.168.8.44Wheres Client A?ClientA is at 192.168.8.44

Caching TableHost NameIP AddressTTLclientA.contoso.msft.192.168.8.4428 seconds

Network Service -*How DNS Data Is Stored and MaintainedDNS ServerZone File: Training.nwtraders.msft.dnsDNS ClientADNS ClientBDNS ClientCNamespace: training.nwtraders.msft Resource record (RR) DNS DNS zone DNS DNS DNS .

Resource records for the zone training.nwtraders.msftHost nameIP addressDNS ClientA192.168.2.45DNS ClientB192.168.2.46DNS ClientC192.168.2.47

Network Service -*What Are Resource Records and Record Types?

Record typeDescriptionAResolves a host name to an IP addressPTRResolves an IP address to a host nameSOAThe first record in any zone file SRVResolves names of servers providing servicesNSIdentifies the DNS server for each zoneMXThe mail serverCNAMEResolves from a host name to a host name

Network Service -*What Is a DNS Zone?

Network Service -*What Are DNS Zone Types?Read/WriteRead-OnlyCopy oflimitedrecords

ZonesDescriptionPrimaryRead/write copy of a DNS databaseSecondaryRead-only copy of a DNS databaseStubCopy of a zone containing limited records

Network Service -*How to Change a DNS Zone Type

Your instructor will demonstrate how to change a DNS zone type

Network Service -*What Are Forward and Reverse Lookup Zones?Namespace: training.nwtraders.msft.DNS Client1DNS Client2DNS Client3DNS Server Authorizedfor trainingDNS Client2 = ?192.168.2.46 = ?

Forward zoneTrainingDNS Client1192.168.2.45DNS Client2192.168.2.46DNS Client3192.168.2.47Reverse zone 1.168.192.in-addr.arpa192.168.2.45DNS Client1192.168.2.46DNS Client2192.168.2.47DNS Client3

Network Service -*How DNS Zone Transfers WorkSecondary ServerPrimary andMaster ServerSOA query for a zoneSOA query answeredIXFR or AXFR query for a zoneIXFR or AXFR query answered(zone transfer)DNS zone transfer DNS servers zone data synchronization() authoritative() .1234

Network Service -*How DNS Notify WorksSecondary ServerPrimary andMaster ServerDNS notifyZone transferDNS notify Primary Zone Zone Authority Secondary Primary Secondary . Source ServerDestination Server1234Resource record is updatedSOA serial number is updated

Network Service -*Lesson: Configuring a DNS ClientHow Preferred and Alternate DNS Servers WorkHow Suffixes Are AppliedHow to Configure a DNS Client

Network Service -*How Preferred and Alternate DNS Servers Work

Network Service -*How Suffixes Are AppliedName query = server1server1.sales.south.nwtraders.comserver1.south.nwtraders.comserver1.nwtraders.com

Network Service -*What Is Delegation of a DNS Zone?The administrator, at the nwtraders.com level of the namespace, delegates authority for training.nwtraders.com and offloads administration of DNS for that part of the namespaceDNS serverDNS serverNamespace: training.nwtraders.msfttraining.nwtraders.msftDelegation() DNS .. training.nwtraders.msftTraining.nwtraders.com now has its own administrator and DNS server to resolve queries in that part of the namespace/organization

Network Service -*Lab : Domain Name System(DNS) LABWindows 2003 Server DNS XP Name Query .DNS Server Record .APTRMXCNAME

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