Name Resolution

1. Name Resolution Presented By Tom Battaglia Thomas Text

2. 4 Section presentation • Section 1 - Resolution Methods Defined • Section 2 - Microsoft Name Resolution • Section 3 - The OSI Model • Section 4 - Troubleshooting Thomas Text

3. Section 1 of 4 Resolution Methods Defined Thomas Text

4. Resolution Methods • What is Name resolution • Computers communicate using IP’s • People communicate using computer names • Name resolution is a result of a client query to get an IP address for a computer name • “Name Server” - The server that can hand out an IP after a query for one is made NOTE: If a client uses an IP to communicate the Name Server is not necessary Thomas Text

5. Resolution Methods • Types of Resolution Methods • Broadcast for NetBIOS Name • WINS - Windows Internet Name Server • DNS - Domain Name Server • DDNS - Dynamic Domain Name Server • Node Type Resolution of Microsoft clients • B-node / P-node / M-node / H-node • LMHOST / HOST Thomas Text

6. Broadcast for NetBIOS "Short" Name Thomas Text

7. Resolution Methods Defined • Broadcast - Characteristics • Routers do not forward Broadcast requests off of the subnet • Only NetBIOS "Short"names can be resolved on the local subnet • Every Client on the subnet processes Broadcast packets Thomas Text

8. Windows Internet Name Service (WINS) Note: Microsoft Windows Clients Only Thomas Text

9. Resolution Methods DefinedWINS • WINS - Server Characteristics • Resolves NetBIOS "Short" Names only • i.e. Batman01 • Client updates dynamic database on WINS server during startup or Nbtstat -RR • Admin can add static entries to WINS • ONLY Services are registered in WINS • WINS Servers exchange entries by being "Push/Pull" partners Thomas Text

10. Resolution Methods DefinedWINS • WINS - Client Characteristics • * Client DOES NOT use secondary unless primary WINS server is down • To resolve a name to an IP the client must be • using a WINS server that the destination server registered with OR • The clients WINS server is a "Push/Pull" partner of the destinations WINS server * NT4 Only. W2K will use Secondary after a delay. Thomas Text

11. Resolution Methods DefinedWINS • WINS – Server Locations Thomas Text

12. Resolution Methods DefinedWINS • WINS – MMC Example Thomas Text

13. Resolution Methods DefinedWINS • WINS – Unique Type Examples WINS Entry Type Service Registered • [00h] Computer Name Workstation Service • [03h] Computer Name Messenger Service for Computer • [20h] Computer Name File Server Service • [BEh] Computer Name Network Monitoring Agent Service • [03h] User Name Messenger Service for the logged on user • [1Bh] Domain Name Domain Master Browser Service – PDC • [1Dh] Domain Name Subnet Master Browser Service Thomas Text

14. Resolution Methods DefinedWINS • WINS – Group Type Examples WINS Entry Type Service Registered • [00h] Domain Name Workstation Service Receives Browser Broadcasts • [1Ch] Domain Name Domain Controllers 1 PDC 24 BDCs • [1Eh] Domain Name Used by Browsers for Elections • [01h] --_MSBROWSE_ Registered by Subnet Master Browser Returned to clients after Query Thomas Text

15. Domain Name Service (DNS) Thomas Text

16. Resolution Methods DefinedDNS • DNS - Server Characteristics • Resolves Fully Qualified Domain Names "FQDN" • i.e. Batman01.us.dell.com. • Integrated Microsoft and UNIX Servers • All Registrations are Statically Entered • Provides Forward Lookup - Name to IP • Provides Reverse Lookup - IP to Name Thomas Text

17. Resolution Methods DefinedDNS • DNS - Client Characteristics • The Client uses Domain Suffixes to Lookup Names • i.e. "us.dell.com" • i.e. "dell.com" • Client WILL use Secondary if Name can not be Found on Primary DNS Server Thomas Text

18. Resolution Methods Defined DNS NT4 Client / Server Setup • DNS – Domain Suffixes Thomas Text

19. Resolution Methods DefinedDNS • DNS – Forward Lookup MMC Example IP Address Host Names IP Alias Thomas Text

20. Resolution Methods DefinedDNS • DNS – Forward Lookup Unix Example IP Address Host Names IP Alias Thomas Text

21. Resolution Methods DefinedDNS • DNS – Reverse lookup MMC Example Host Names IP - First Octet Thomas Text

22. Resolution Methods DefinedDNS • DNS – Reverse lookup Unix Example Filename Host Names IP - First Octet Thomas Text

23. Dynamic Domain Name Service(DDNS) Thomas Text

24. Resolution Methods DefinedDDNS • DDNS - Server Characteristics • Resolves Fully Qualified Domain Names "FQDN" • i.e. Batman01.aus.amer.dell.com. • ONLY Microsoft W2K servers • Some Registrations are Statically Entered • Provides Forward Lookup - Name to IP • Provides Reverse Lookup - IP to Name • Proxy Lookup to the WINS Server Thomas Text

25. Resolution Methods DefinedDDNS • DDNS - Client Characteristics • The Client uses Domain Suffixes to Lookup Names • i.e. "aus.amer.dell.com" • i.e. "amer.dell.com" • Client WILL use Secondary if Name can not be Found on Primary DNS Server • Registrations are Dynamically Entered when the W2K client uses a DDNS server Thomas Text

26. Resolution Methods DefinedDDNS W2K Client / Server Setup • DDNS – Domain Suffixes Thomas Text

27. Resolution Methods DefinedDDNS • DDNS – Forward LookupMMC Example IP Address Host Names Thomas Text

28. Resolution Methods DefinedDDNS • DDNS – Reverse lookup MMC Example • Not currently implemented at Dell on the W2K DDNS platform Thomas Text

29. Section 2 of 4 Microsoft Name Resolution Thomas Text

30. Microsoft Name Resolution • Part 1 - Resolution Methods • B-node / P-node / M-node / H-node • LMHOST File • HOST File • Part 2 - Combined Resolution Methods • NetBIOS • DNS Thomas Text

31. Part 1 Resolution Methods Thomas Text

32. Microsoft Name Resolution • B-Node - Characteristics • Uses Broadcast NetBIOS Name Queries for Name Registration and Resolution • B-Node Limitations: (1) Broadcasts Disturb every node on the Network (2) Routers Typically do not Forward Broadcasts, so only NetBIOS Names on the Local Network can be Resolved Thomas Text

33. Microsoft Name Resolution • P-Node - Characteristics • Uses NetBIOS Name Server (NBNS) - Typically a WINS Server • P-Node Limitations: (1) If the Server is not Registered with WINS the Client can not Resolve it (2) If the NBNS is "Down" the Client May not Resolve or will use the Secondary with Degraded Results Thomas Text

34. Microsoft Name Resolution • M-Node - Characteristics • Uses B-Node First • Uses P-Node if B-Node does not Resolve • M-Node Limitations: (1) Broadcasts Disturb Every Node on the Network (2) If the NBNS is "Down" the Client May not Resolve or will use the Secondary with Degraded Results Thomas Text

35. Microsoft Name Resolution • H-Node - Characteristics • Uses P-Node First • Uses B-Node if B-Node does not Resolve • H-Node Advantages: (1) It Does Not Use Broadcasts First (2) It Will Resolve Faster Using WINS and cut down on Network Traffic NOTE: This is the method Microsoft uses for all their Windows platforms Thomas Text

36. Microsoft Name Resolution • LMHOST File - Characteristics • Used to resolve NetBIOS "Short" Names • Can have Entries Cached from file • Located in [%systemroot%\system32\drivers\etc] • LMHOST File Limitations: (1) Can hold only 128 entries (2) If a Name Changes all LMHOST Files Need to be Updated Thomas Text

37. Microsoft Name Resolution • LMHOST File Example LMHOST File - No Extension LMHOST Sample File Examples Thomas Text

38. Microsoft Name Resolution • HOST File - Characteristics • Used to resolve FQDN Names • Can have Entries Cached from file • Located in [%systemroot%\system32\drivers\etc] • HOST File Limitations: (1) If a Name Changes all HOST Files Need to be Updated Thomas Text

39. Microsoft Name Resolution • HOST File Example HOST File - No Extension Examples Thomas Text

40. Part 2Combined Resolution Methods Thomas Text

41. Microsoft Name Resolution • All Microsoft Platforms - NetBIOS • Uses B-Node if no WINS Server Specified • Uses H-Node Resolution if a WINS Server is Specified • If System Fails to Register with WINS it will Result in B-Node until it can Contact the WINS Server • Some Commands - Net View and Nbtstat Thomas Text

42. Microsoft Name Resolution M-Node LMHOST Cache Broadcast WINS LMHOST File If Configured for "DNS for WINS Resolution (NT4)" HOST File DNS Server H-Node LMHOST Cache WINS Broadcast LMHOST File If Configured for "DNS for WINS Resolution (NT4)" HOST File DNS Server M-Node LMHOST Cache Broadcast LMHOST File P-Node LMHOST Cache WINS LMHOST File NetBIOS Resolution Thomas Text

43. Microsoft Name Resolution H-Node Cache WINS Broadcast LMHOST File HOST File DNS Server Time Out • An example of name resolution would be like calling information to get the # - (IP Address) • Try to remember the # • Call information to get a # for a name • The operator can put your call through • If the # is unlisted you might need to go in your front yard and call their name • Check the Counter for Pieces of Paper • You might check your personal phone list • Look it up in the phone book (FQDN) • Give up and go shopping Thomas Text

44. Microsoft Name Resolution • All Microsoft Platforms - DNS / DDNS • Client will look on Server and Query Using the Domain Suffixes • Some Commands - Ping, Ftp, and Telnet Suffix Search Order DNS Server Thomas Text

45. Microsoft Name Resolution • Microsoft Reference Articles • Q105997 - Differences Between the HOSTS and LMHOSTS Files in Windows NT • Q119493 - NetBIOS over TCP-IP Name Resolution and WINS • Q120642 - TCP-IP & NBT Configuration Parameters for Windows NT and Windows 2000 • Q142042 - Description of TCP-IP Node-Type Settings in Windows 95-98 • Q142309 - NetBIOS Name Resolution Using DNS and the HOSTS File • Q158474 - Windows TCP-IP Registry Entries • Q160177 - Default Node Type for Microsoft Clients • Q167640 - Automatically Changing the Node Type of a Windows NT Workstation Thomas Text

46. Section 3 of 4 The OSI Model Thomas Text

47. Open Systems Interconnection (OSI) Model • OSI Characteristics • Describes how information from a software application in one computer moves through a network medium to a software application in another computer • Developed by the International Organization for Standardization (ISO) in 1984 • Each layer being implemented independently enables the solutions offered by one layer to be updated without adversely affecting the other layers Thomas Text

48. Open Systems Interconnection (OSI) Model • OSI Characteristics • Data Encapsulation and Decapsulation occurs as each layer passes data up and down the stack • Layered approach for ease of Learning, Modular Engineering, Interoperability and Eases Standards Development • Ethernet = Frames • TCP/IP = Packets Thomas Text

49. Open Systems Interconnection (OSI) Model • Layer 7 — Application layer • Layer 6 — Presentation layer • Layer 5 — Session layer • Layer 4 — Transport layer • Layer 3 — Network layer • Layer 2 — Data Link layer • Layer 1 — Physical layer Implemented with software Implemented with Software & Hardware Thomas Text

50. Open Systems Interconnection (OSI) Model • "FYI" OSI Compared to TCP/IP Stack • Application • Presentation • Session • Transport • Network • Data Link • Physical OSI 7 LayersTCP/IP 4 Layers • Application • Transport • Internet • Interface Thomas Text