1. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 1 Lesson 17 Domain Name System (DNS)

2. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 2 Domain Name System (DNS) Overview of DNS DNS zones How DNS works DNS resource records DNS message format DNS messages

3. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 3 Overview of DNS DNS namespace Domain names Top-level domains Resource records (RRs) DNS query operation DNS update operation

4. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 4 Domain Name Space

5. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 5 DNS Zones Standard primary Standard secondary Active Directory-integrated Stub Reverse-lookup

6. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 6 Zones versus Domains

7. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 7 Overview of DNS (continued) Reverse queries Inverse queries DNS query classes DNS resolver DNS resolver cache Negative caching

8. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 8 Overview of DNS (continued) Zone transfer Incremental zone transfers Active Directory-integrated zone replication Delegation of domains

9. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 9 Forwarder and Slave DNS Servers DNS clientDNS Server A DNS clientDNS Server B DNS clientDNS Server C DNS Server D (Forwarder) To external DNS servers Single Site

10. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 10 Overview of DNS (continued) Round robin load balancing DNS dynamic updates IPv6 support DNS extension mechanisms DNS security

11. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 11 How DNS Works Configuring DNS client functions Resolving names Resolving aliases Dynamically updating DNS Transferring zone information

12. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 12 DNS Resource Records Common set of information Owner TTL Class Type Record-specific data Common RRs A, AAAA, CNAME, KEY, MX, NXT, OPT, PTR, SIG, SRV

13. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 13 Generic DNS Query Message Format Question Entries (variable length) Answer RRs (variable length) Authority RRs (variable length) Additional RRs (variable length) DNS Header (fixed length)

14. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 14 DNS Message Header Transaction ID Flags Question RR Count Answer RR Count Authority RR Count Additional RR Count

15. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 15 DNS Message Flags Field Request/Response Operation Code Authoritative Answer Truncation Recursion Desired Recursion Available Reserved Return Code 00 0

16. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 16 Question Entry Format Question Name Question Type Question Class = 0x00-01...

17. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 17 DNS RR Format RR Name Record Type Record Class Time to Live Resource Data Length Resource Data = 0x00-01...

18. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 18 The RR Name as a Pointer 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 1 1 1 RR Name 1100000000001100 Indicates Pointer C0-0C Indicates 12th byte Offset

19. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 19 DNS Update Message Format Identification Flags Number of Zone Entries Number of Prerequisite RRs Number of Update RRs Number of Additional RRs Zone Entry Prerequisite RRs Update RRs Additional RRs...

20. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 20 DNS Update Message Flags Field Request/Response Operation Code Reserved Return Code 0 00 101 00000

21. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 21 DNS Messages Name Query Name Query Response Reverse Name Query Name Update Name Update Response

22. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 22 Review Overview of DNS DNS zones How DNS works DNS resource records DNS message format DNS messages