Name Resolution Presented By Tom Battaglia Thomas Text

Name Resolution Presented By Tom Battaglia Thomas Text

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

Section 1 of 4 Resolution Methods Defined Thomas Text

Resolution Methods n What is Name resolution u Computers communicate using IP’s u People communicate using computer names u u 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

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

Broadcast for Net. BIOS "Short" Name Thomas Text

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

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

Resolution Methods Defined WINS n WINS - Server Characteristics u u Resolves Net. BIOS "Short" Names only • i. e. Batman 01 Client updates dynamic database on WINS server during startup or Nbtstat -RR u Admin can add static entries to WINS u ONLY Services are registered in WINS u WINS Servers exchange entries by being "Push/Pull" partners Thomas Text

Resolution Methods Defined WINS n WINS - Client Characteristics u u * Client DOES NOT use secondary unless primary WINS server is down To resolve a name to an IP the client must be t using a WINS server that the destination server registered with OR t The clients WINS server is a "Push/Pull" partner of the destinations WINS server * NT 4 Only. W 2 K will use Secondary after a delay. Thomas Text

Resolution Methods Defined WINS n WINS – Server Locations Thomas Text

Resolution Methods Defined WINS n WINS – MMC Example Thomas Text

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

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

Domain Name Service (DNS) Thomas Text

Resolution Methods Defined DNS n DNS - Server Characteristics Resolves Fully Qualified Domain Names "FQDN" • i. e. Batman 01. us. dell. com. u Integrated Microsoft and UNIX Servers u u All Registrations are Statically Entered u Provides Forward Lookup - Name to IP u Provides Reverse Lookup - IP to Name Thomas Text

Resolution Methods Defined DNS n DNS - Client Characteristics u u 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

Resolution Methods Defined DNS n DNS – Domain Suffixes NT 4 Client / Server Setup Thomas Text

Resolution Methods Defined DNS n DNS – Forward Lookup MMC Example IP Address Host Names IP Alias Thomas Text

Resolution Methods Defined DNS n DNS – Forward Lookup Unix Example IP Address Host Names IP Alias Thomas Text

Resolution Methods Defined DNS n DNS – Reverse lookup MMC Example Host Names IP - First Octet Thomas Text

Resolution Methods Defined DNS n DNS – Reverse lookup Unix Example Filename Host Names IP - First Octet Thomas Text

Dynamic Domain Name Service (DDNS) Thomas Text

Resolution Methods Defined DDNS n DDNS - Server Characteristics Resolves Fully Qualified Domain Names "FQDN" • i. e. Batman 01. aus. amer. dell. com. u ONLY Microsoft W 2 K servers u u Some Registrations are Statically Entered u Provides Forward Lookup - Name to IP u Provides Reverse Lookup - IP to Name u Proxy Lookup to the WINS Server Thomas Text

Resolution Methods Defined DDNS n DDNS - Client Characteristics u 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 u Registrations are Dynamically Entered when the W 2 K client uses a DDNS server u Thomas Text

Resolution Methods Defined DDNS n DDNS – Domain Suffixes W 2 K Client / Server Setup Thomas Text

Resolution Methods Defined DDNS n DDNS – Forward Lookup MMC Example IP Address Host Names Thomas Text

Resolution Methods Defined DDNS n DDNS – Reverse lookup MMC Example u Not currently implemented at Dell on the W 2 K DDNS platform Thomas Text

Section 2 of 4 Microsoft Name Resolution Thomas Text

Microsoft Name Resolution n Part 1 - Resolution Methods B-node / P-node / M-node / H-node u LMHOST File u n Part 2 - Combined Resolution Methods Net. BIOS u DNS u Thomas Text

Part 1 Resolution Methods Thomas Text

Microsoft Name Resolution n B-Node - Characteristics u u Uses Broadcast Net. BIOS 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 Net. BIOS Names on the Local Network can be Resolved Thomas Text

Microsoft Name Resolution n P-Node - Characteristics u u Uses Net. BIOS 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

Microsoft Name Resolution n M-Node - Characteristics u Uses B-Node First u Uses P-Node if B-Node does not Resolve u 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

Microsoft Name Resolution n H-Node - Characteristics u Uses P-Node First u Uses B-Node if B-Node does not Resolve u 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

Microsoft Name Resolution n LMHOST File - Characteristics u Used to resolve Net. BIOS "Short" Names u Can have Entries Cached from file u Located in [%systemroot%system 32driversetc] u LMHOST File Limitations: (1) Can hold only 128 entries (2) If a Name Changes all LMHOST Files Need to be Updated Thomas Text

Microsoft Name Resolution n LMHOST File Example LMHOST File - No Extension LMHOST Sample File Examples Thomas Text

Microsoft Name Resolution n HOST File - Characteristics u Used to resolve FQDN Names u Can have Entries Cached from file u Located in [%systemroot%system 32driversetc] u HOST File Limitations: (1) If a Name Changes all HOST Files Need to be Updated Thomas Text

Microsoft Name Resolution n HOST File Example HOST File - No Extension Examples Thomas Text

Part 2 Combined Resolution Methods Thomas Text

Microsoft Name Resolution n All Microsoft Platforms - Net. BIOS u u 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

Microsoft Name Resolution M-Node P-Node M-Node H-Node LMHOST Cache Broadcast WINS Broadcast LMHOST File If Configured for "DNS for WINS Resolution (NT 4)" HOST File DNS Server Broadcast LMHOST File Net. BIOS Resolution Thomas Text

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

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

Microsoft Name Resolution n Microsoft Reference Articles u Q 105997 - Differences Between the HOSTS and LMHOSTS Files in Windows NT u Q 119493 - Net. BIOS over TCP-IP Name Resolution and WINS u Q 120642 - TCP-IP & NBT Configuration Parameters for Windows NT and Windows 2000 u Q 142042 - Description of TCP-IP Node-Type Settings in Windows 95 -98 u Q 142309 - Net. BIOS Name Resolution Using DNS and the HOSTS File u Q 158474 - Windows TCP-IP Registry Entries u Q 160177 - Default Node Type for Microsoft Clients u Q 167640 - Automatically Changing the Node Type of a Windows NT Workstation Thomas Text

Section 3 of 4 The OSI Model Thomas Text

Open Systems Interconnection (OSI) Model n OSI Characteristics u Describes how information from a software application in one computer moves through a network medium to a software application in another computer u u 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

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

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

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

Open Systems Interconnection (OSI) Model Each layer communicates with three other OSI layers: 1. The layer directly above it, 2. The layer directly below it 3. Its peer layer in other networked device Application n Presentation n Session n Transport n Network n Data Link n Physical n Upper Layer "Service User" Peer-to-Peer Communication Protocol Data Units (PDU) Lower Layer "Service Provider" Thomas Text

Open Systems Interconnection (OSI) Model Application n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Layer 2 n Layer 1 n q q Interface to Application Interface to User UDP Application examples Ø DHCP Ø BOOTP Ø TFTP TCP Application examples Ø HTTP Ø FTP Ø TELNET Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Presentation n Layer 5 n Layer 4 n Layer 3 n Layer 2 n Layer 1 n q q q "Translator" Encryption Decryption Compression Decompression Architecture Independent data transfer format. i. e. Ø MPEG Ø Gif Ø Jpeg Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Session n Layer 4 n Layer 3 n Layer 2 n Layer 1 n q q "Coordinator" Manage User Sessions Ø Establish Connection Ø Manage Connection Ø Terminate Connection Report upper layer errors Protocols Ø Apple. Talk Ø Session Control Protocol Ø DECnet Phase 5 Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Transport n Layer 3 n Layer 2 n Layer 1 n q q q "Segmenter" Reliable Packet Delivery Flow Control Multiplexing Error Checking Protocols Used Ø TCP Ø UDP Ø SPX Ø Net. BEUI Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Network n Layer 2 n Layer 1 n q q q q "Packet" (Data gram) Logical Addressing Path Determination (Routing) Connectionless Best-Effort-Delivery Address Res. Protocol -ARP Ø IP to MAC Routed Protocols Ø IP / IPX / ICMP Routing Protocols Ø OSPF / RIP / BGP Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Data Link n Layer 1 n q q q q "Frame" Switches Operate Here All devices talk MAC Header Contains MAC Address Error Notification Network Topology Defined Flow Control Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Data Link n Layer 1 n q Data Link Layer Sub layers q Logical Link Control - LLC Ø 802. 2 Ø Connectionless & Connection Oriented q Media Access Control - MAC Ø Manage protocol access to the physical layer Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Data Link n Layer 1 n Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Layer 2 n Physical n q q q q "Link" Changes data to electrical impulses Transmits "Bits" onto the Wire Removes "Bits" off the Wire Physical error checking Does not add or take away from the Frame Concerned with Physical protocol and not Data Protocol Thomas Text

Open Systems Interconnection (OSI) Model Layer 7 n Layer 6 n Layer 5 n Layer 4 n Layer 3 n Layer 2 n Physical n q q Maintains the Physical Link Defines the physical medium Ø Voltage levels & timings Ø Data Rates Ø Transmission Distance Ø Connectors Ø Cables Thomas Text

Section 4 of 4 Troubleshooting Thomas Text

Troubleshooting n Part 1 - Basic Network Troubleshooting n Part 2 - Net. BIOS Troubleshooting u n Broadcast / WINS / LMHOST File Part 3 - FQDN Troubleshooting u DNS / DDNS / Host File Thomas Text

Part 1 Basic Network Troubleshooting Thomas Text

Troubleshooting Basics n Client Considerations u ONLY GATHER FACTS………. . • u Is it "Slow" or "Not Working"? • u They Say "Last Week" …… It's Really "Never" What Changed? • u They Say "No One" ………It's Really "Everyone Can" When Did it Work Last? • u They Say "It's Dead" ……… It's Really been "Slow" Once Today Can Other Clients get to the Server? • u Don't trust the end user to evaluate. They Say "Nothing" ……… It's Really their Kids Game They Installed Is the Client Properly Configured? • They Say "Yes" ………. . They Don't know what a Computer is Thomas Text

Troubleshooting Basics n Server Considerations u ONLY GATHER FACTS………. . u Is it Static or DHCP? u Can the Server Resolve Names? u When Did it Work Last? u What Changed? u Is the Server Properly Configured? Thomas Text

Troubleshooting Basics n Parts to Troubleshoot u u Separate the network from the Servers t Cables, Switches and Routers are the Net t Computers are the Clients and Servers t If the Network has a Problem Usually Several People are Affected Check the Physical Layer t Is it the Correct Cable t Is there a Link Light t Does another Computer work in the port Thomas Text

Troubleshooting Basics n Parts to Troubleshoot u Check the Computer Configuration • http: //inside. us. dell. com/it/is/network/ Configuration Docs Thomas Text

Troubleshooting Basics n Parts to Troubleshoot u u Check the Computer Configuration Set CLASSID for W 2 K DHCP Clients Capital W 2 K Thomas Text

Troubleshooting Basics n Parts to Troubleshoot u Check the Computer Configuration Domain Suffixes Subnet Mask WINS & DNS Servers Class ID Thomas Text

Troubleshooting Basics n Remove Name Resolution From The Test u u u PING Remote by IP Ping Gateway by IP Ping Loopback (127. 0. 0. 1) Map Drive by IP i. e. net use * \10. 180. 12. 26c$ Tracert to IP i. e. tracert 10. 180. 12. 26 "Net View" to IP i. e. net view \10. 180. 12. 26 NOTE: Resolve ALL IP Issues Prior to Troubleshooting Name Resolution Issues Thomas Text

Troubleshooting Basics n PING IP Example Try to Resolve Name Resolved Thomas Text

Troubleshooting Basics n Tracert Example Found Not Found Thomas Text

Troubleshooting Basics n Netstat Syntax "/? " Display Help Switches Thomas Text

Troubleshooting Basics n Netstat -a Example Port State Protocol Thomas Text

Troubleshooting Basics n Netstat -n Example Port State Protocol Thomas Text

Troubleshooting Basics n Netstat -r Example Default Gateway Remote Thomas Text

Troubleshooting Basics n Netstat -s Example Is Data Moving ? Thomas Text

Part 2 Net. BIOS Troubleshooting Thomas Text

Troubleshooting NBNS (WINS) n Client Considerations u Can Not Login to the Domain • u Can Not Map a Drive by Name • u "No Domain Controller Found" "Host Name Not Found" Can Not "Net View" a computer • "Host Name Not Found" u What WINS Server are they using u Can Other Computers Map Drives by Name u Does Not Need to Register with WINS to Resolve Thomas Text

Troubleshooting NBNS (WINS) n Server Considerations u Are all the Services Registered in WINS? • u The Name Resolution is up to the Client if all the Server Services are Registered in WINS If the Server is down several people are having the SAME problem(s) Thomas Text

Troubleshooting NBNS (WINS) n Add Name Resolution To The Test u "Nbtstat" to "Short Name" • u "Net View" to "Short Name" • u i. e. net view \ausgnsnpt 01 Map Drive by "Short Name" • u i. e. nbtstat -a \ausgnsnpt 01 i. e. net use * \ausgnsnpt 01c$ PING Remote by "Short Name" • i. e. Ping ausgnsnpt 01 Thomas Text

Troubleshooting NBNS (WINS) n Nbtstat Syntax "/? " Display Help Switches Thomas Text

Troubleshooting NBNS (WINS) n Nbtstat -a Example "-a" Remote Services & MAC "-n" Local Services NO MAC Thomas Text

Troubleshooting NBNS (WINS) n Nbtstat -c Example "-c" Cache "-r" Resolved Thomas Text

Troubleshooting NBNS (WINS) n Nbtstat -s and -RR Example "-s or -S" Sessions "-RR" Re. Register with WINS Thomas Text

Troubleshooting NBNS (WINS) n Net View Syntax and Example Show Browse List "Short Name" Thomas Text

Troubleshooting NBNS (WINS) n Net Use Syntax and Example Map next Drive Letter Ask for Password Delete Map Thomas Text

Troubleshooting NBNS (WINS) n PING Example Note: PING is a DNS Command for FQDN but can be used to troubleshoot Net BIOS FQDN Name Resolved by DNS "Short Name" Resolved by Broadcast or WINS Thomas Text

Troubleshooting NBNS (WINS) n LMHOST File Clear the LMHOST file if not needed or you are troubleshooting Thomas Text

Part 3 FQDN Troubleshooting Thomas Text

Troubleshooting DNS/DDNS (FQDN) n Client Considerations u Does the App use FQDNs? u Is the Domain Suffix Correct? u Check for the correct Name Server u Is the IP Address in DNS or DDNS • • u us. dell. com - Legacy aus. amer. dell. com - W 2 K Can Not Map a Drive by FQDN Thomas Text

Troubleshooting DNS/DDNS (FQDN) n Server Considerations u Is the Name in DNS or DDNS? • u The Name Resolution is up to the Client if the server is in DNS or DDNS it has met the minimum requirements If the Server is down several people are having the SAME problem(s) Thomas Text

Troubleshooting DNS/DDNS (FQDN) n NSLookup Syntax Show Commands Thomas Text

Troubleshooting DNS/DDNS (FQDN) n NSLookup Example Authoritative amer. dell. com DDNS Server Query Returned Non-Authoritative amer. dell. com DDNS Server Query Returned Thomas Text

Troubleshooting DNS/DDNS (FQDN) n NSLookup Example Non-Authoritative us. dell. com DDNS Server Query Returned No DNS Entry Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Syntax Show Syntax Switches Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Example u PING Loop Back Address • TCP/IP is Installed Properly Loop Back Address Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Example Domain Suffix Search Order Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Example Domain Suffix Search Order Ping Short Name WINS Responded with "Short Name" Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Example Domain Suffix Search Order Ping Short Name DDNS Responded with FQDN Thomas Text

Troubleshooting DNS/DDNS (FQDN) n PING Example u PING Loop Back Name in Host File • TCP/IP is Installed Properly • Host File is Working Loop Back Name "Localhost" Thomas Text

Name Resolution Presented By Tom Battaglia Thomas Text