Domain Name System (DNS)

Network Service -2 What Is a Domain Namespace? Root Domain Subdomains Second-Level Domain Top-Level Domain FQDN: server1.sales.south.nwtraders.com FQDN: server1.sales.south.nwtraders.com south nwtraders com sales west east org net Host: server1

Network Service -3 Standards for DNS Naming The following characters are valid for DNS names: A-Z a-z 0-9 Hyphen (-) The underscore (_) is a reserved character

Network Service -4 What Are the Components of a DNS Solution? DNS Servers on the InternetDNS ServersDNS Clients Root “.”.com.edu Resource Record Resource Record Resource Record Resource Record

Network Service -5 What Is a DNS Query? DNS clients and DNS servers both initiate queries for name resolution An authoritative DNS server for the namespace of the query will either:  Check the cache, check the zone, and return the requested IP address  Return an authoritative, “ No ” A non-authoritative DNS server for the namespace of the query will either:  Forward the unresolvable query to a specific query server called a Forwarder  Use root hints to locate an answer for the query DNS server 에 name resolution 요청하는 방법인 DNS Query 가 Recursive( 재귀 ) 와 iterative( 반복 ) Query 2 가지가 있다.

Network Service -6 How Recursive Queries Work Computer1 Recursive query for mail1.nwtraders.com Recursive( 재귀 ) Query 는 DNS client 가 Local DNS Server 에 Query 를 보내는 종류의 Query 로 Query 에 대한 응답이 올 때 까지 Query 를 계속적으로 Query 보내는 방법을 말한다. DNS server checks the forward lookup zone and cache for an answer to the query Database Local DNS Server

Network Service -7 How Root Hint Works Root hints 란 Local DNS Server 에 Query 에 대한 IP addresses 정 보가 없을 때 Local DNS Server 가 DNS root servers 에게 Query 를 보내는 것을 말한다. microsoft Cluster of DNS Servers Cluster of DNS Servers Root Hints DNS Server Cluster of Root (.) Servers Cluster of Root (.) Servers com Computer1

Network Service -8 How Iterative Queries Work Iterative( 반복 ) Query 란 Root server 가 하는 것이다. 이름 풀이를 할 때 영역 파일에 정보를 가지고 있을 때만 이름 풀이를 할 것이다. 만일 그렇지 않다면 다른 DNS server 들에 Query 를 보내는 것을 말한다. Computer1 Local DNS Server Local DNS Server nwtraders.com Root Hint (.).com Recursive query for mail1.nwtraders.com Iterative Query Ask.com Ask nwtraders.com Authoritative Response

Network Service -9 How Forwarders Work Forwarder( 전달자 ) 는 외부 DNS(Domain Name System) 이름에 대한 DNS 쿼리를 네트워크 외부의 DNS 서버에 Forward( 전달 ) 하는 데 사용되는 네트워크의 DNS 서버입니다. Forwarder( 전달자 ) 는 외부 DNS(Domain Name System) 이름에 대한 DNS 쿼리를 네트워크 외부의 DNS 서버에 Forward( 전달 ) 하는 데 사용되는 네트워크의 DNS 서버입니다. Computer1 nwtraders.com Root Hint (.).com Iterative Query Ask.com Ask nwtraders.com Authoritative Response Local DNS Server Local DNS Server Forwarder Recursive query for mail1.nwtraders.com Recursive Query

Network Service -10 How DNS Server Caching Works Caching 이란 최근에 접근한 정보를 액세스를 빠르게 하기 위해서 메모리에 저장하는 과정을 말한다. Where’s Client A? Client1 Client2 ClientA ClientA is at Where’s Client A? ClientA is at Caching Table Host NameIP AddressTTL clientA.contoso.msf t seconds

Network Service -11 How DNS Data Is Stored and Maintained DNS Server Zone File: Training.nwtraders.msft.dns DNS ClientA Resource records for the zone training.nwtraders.msft Host nameIP address DNS ClientA DNS ClientB DNS ClientC DNS ClientB DNS ClientC Namespace: training.nwtraders.msft Resource record (RR) 는 DNS 쿼리를 처리하는데 사용되는 정보를 포함하고 있는 표준 DNS 데이터베이스 구조 zone 은 DNS 데이터베이스에서 DNS 서버에 의해 하나의 별개 항목으로 관리되는 DNS 트리의 연속되어 있는 부분.

Network Service -12 What Are Resource Records and Record Types? Record typeDescription AResolves a host name to an IP address PTRResolves an IP address to a host name SOAThe first record in any zone file SRVResolves names of servers providing services NSIdentifies the DNS server for each zone MXThe mail server CNAMEResolves from a host name to a host name

Network Service -13 What Is a DNS Zone? Nwtraders West South Support Sales Training North

Network Service -14 What Are DNS Zone Types? ZonesDescription Primary Read/write copy of a DNS database Secondary Read-only copy of a DNS database Stub Copy of a zone containing limited records Read/Write Read-Only Copy of limited records

Network Service -15 How to Change a DNS Zone Type Your instructor will demonstrate how to change a DNS zone type

Network Service -16 What Are Forward and Reverse Lookup Zones? Namespace: training.nwtraders.msft. DNS Client1 DNS Client2 DNS Client3 DNS Server Authorized for training DNS Server Authorized for training Forwar d zone Training DNS Client DNS Client DNS Client Revers e zone in- addr.arpa DNS Client DNS Client DNS Client3 DNS Client2 = ? = ?

Network Service -17 How DNS Zone Transfers Work Secondary Server Primary and Master Server SOA query for a zone SOA query answered IXFR or AXFR query for a zone IXFR or AXFR query answered (zone transfer) DNS zone transfer 는 DNS servers 에서 zone data 를 synchronization( 동기화 ) 및 authoritative( 인증 ) 작업을 한다

Network Service -18 How DNS Notify Works Secondary Server Primary and Master Server DNS notify Zone transfer DNS notify 는 Primary 의 Zone 데이터베이스가 수정되었음을 해당 Zone 의 Authority 를 갖는 Secondary 서버로 알려주어 Primary 와 Secondary 네임서버의 동적 동기화를 가능케 한다. Source Server Destination Server Resource record is updated SOA serial number is updated

Network Service -19 Lesson: Configuring a DNS Client How Preferred and Alternate DNS Servers Work How Suffixes Are Applied How to Configure a DNS Client

Network Service -20 How Preferred and Alternate DNS Servers Work 1. The preferred DNS server is the one that the client tries first 2. If the preferred server fails, the client tries the alternate DNS server 3. Optionally, you can enter a whole list of alternate DNS servers 4. The preferred and alternate DNS servers specified on the Properties page automatically appear at the top of this list, and preferred and alternate servers are queried in the order they are listed

Network Service -21 How Suffixes Are Applied Suffix Selection option Suffix Selection option Domain suffix search list Connection Specific Suffix Name query = server1 server1.sales.south.nwtraders.com server1.south.nwtraders.com server1.nwtraders.com

Network Service -22 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 namespace DNS server Namespace: training.nwtraders.msft training.nwtraders.msft Delegation( 위임 ) 은 도메인 이름에 대한 책임을 네트워크상의 각기 다른 DNS 서버에 분산시키는 프로세스.. training.nwtraders.msft Training.nwtraders.com now has its own administrator and DNS server to resolve queries in that part of the namespace/organization

Network Service -23 Lab : Domain Name System(DNS) LAB 1.Windows 2003 Server 를 이용하여 DNS 서버 를 구성하고 XP 에서 Name Query 를 실행한다. 2.DNS Server 에 다음 Record 를 구성한다. 1.A 2.PTR 3.MX 4.CNAME