Hostname Resolution

469
-1

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
469
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
4
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Hostname Resolution

  1. 1. CHAPTER Host Name Resolution DNS and WINS
  2. 2. Chapter Objectives <ul><li>Explain the process of hostname resolution to IP address on the Internet </li></ul><ul><li>Describe the purpose of the HOSTS, LMHOSTS files </li></ul><ul><li>Show how the HOSTS and LMHOSTS file could be modified to resolve abbreviated names to IP addresses </li></ul>
  3. 3. Module Host Name Resolution Process
  4. 4. Name Resolution <ul><li>Resolve names to IP addresses and vice versa </li></ul><ul><ul><li>www.calstatela.edu <-> 130.182.1.60 </li></ul></ul><ul><li>Names </li></ul><ul><ul><li>TCP/IP host names </li></ul></ul><ul><ul><li>WINS names a.k.a. NetBIOS names </li></ul></ul>
  5. 5. Finding an IP Address of a Domain <ul><li>ping www.ganesan.com </li></ul><ul><li>tracert www.ganesan.com </li></ul><ul><ul><li>Shows the number of hops to the destination </li></ul></ul>
  6. 6. TCP/IP Host Name Example
  7. 7. WINS or NetBIOS Names
  8. 8. Current Computer Names <ul><li>Only the TCP/IP host name is currently in widespread use </li></ul><ul><li>The Windows based name or the NetBIOS name as it is known is not widely used anymore </li></ul><ul><ul><li>This may be retained for compatibility with older systems </li></ul></ul>
  9. 9. Internet Host Names .com .edu .org Etc. ganesan.com courses.ganesan.com A unique identifier known as the Fully Qualified Domain Name (FQDN)
  10. 10. Internet Host Name Resolution <ul><li>First, a local file known as HOSTS is checked to resolve the name to an IP address </li></ul><ul><li>If a corresponding entry is not found in the HOST file, the information is transmitted to a DNS server for name resolution </li></ul><ul><li>A cascade of DNS servers at different locations may get involved in the resolution process </li></ul>
  11. 11. End of Module
  12. 12. Module Hosts File
  13. 13. Sample HOSTS File
  14. 14. Sample Entry in the HOSTS File
  15. 15. Host Name Resolution Example
  16. 16. HOSTS File <ul><li>HOSTS file location </li></ul><ul><ul><li>C:Windows in Windows 9x </li></ul></ul><ul><ul><li>C:WINNTsystem32driversetc in Windows NT </li></ul></ul><ul><ul><li>C:Windowssystem32driversetc in Windows XP </li></ul></ul><ul><li>The file could be searched as well </li></ul><ul><li>The extension of the file may be .SAM </li></ul><ul><li>Note: </li></ul><ul><ul><li>Store the file as “HOSTS” after modification with Notepad to avoid it being given a Notepad file extension </li></ul></ul>
  17. 17. Redirection to DNS <ul><li>If there are no entries in the HOSTS file, the request is redirected to a DNS on the network </li></ul><ul><li>Multiple DNSs may have to be consulted before the name is mapped to an IP address </li></ul><ul><li>Domain names must also be registered with InterNIC or a similar organization </li></ul>
  18. 18. DNS Perspective of Name Resolution courses.ganesan.com .com root domain points to the DNS server At Pacbell Pacbell DNS server points to the DNS server at Ganesan.com DNS server at ganesan.com locates the host “course”
  19. 19. Domain Name Hosting: Another Example courses.ganesan.com InterNIC points to the DNS server at ganesan.com DNS server at ganesan.com locates the host “course”
  20. 20. End of Module
  21. 21. Module LMHOST File
  22. 22. Windows or NetBIOS Names kumar nanda ganesan Domain
  23. 23. Uniform Naming Convention (UNC) <ul><li>Applies to finding a resource on a local network </li></ul><ul><li>indowsnamefolderfile </li></ul><ul><li>An example of windowsname could be a server name </li></ul><ul><li>umarsalesannual.doc </li></ul><ul><li>Note: FQDN applies to the Internet where a website, for example, is located using this name </li></ul><ul><li>Find the FQDN of your computer, if it is connected to the Internet </li></ul>
  24. 24. Windows Name Resolution <ul><li>First a local file known as LMHOSTS is checked to resolve the name to an IP </li></ul><ul><li>If a corresponding entry is not found in the HOST file, the information is transmitted to a WINS server for name resolution </li></ul><ul><li>WINS </li></ul><ul><ul><li>Windows Internet Name Service </li></ul></ul>
  25. 25. Sample Partial LMHOSTS File Inclusion of lmhosts files from other computers.
  26. 26. Sample Entry in LM HOSTS File
  27. 27. Intranet Example kumar nanda ganesan Domain Internet Web Server
  28. 28. NetBIOS Name Resolution with LMHOSTS Entry
  29. 29. Access Path with LMHOSTS Entry kumar nanda ganesan Internet Web Server Access Client
  30. 30. NetBIOS Name Resolution without LMHOSTS Entry IE5 searches for a web address match and substitutes www.ganesan.com
  31. 31. Access Path without LMHOSTS Entry kumar nanda ganesan Internet Web Server Access Client Access is through the Internet.
  32. 32. IE5 Search for Web Address Match
  33. 33. LMHOSTS File <ul><li>LMHOSTS file location </li></ul><ul><ul><li>C:Windows in Windows 9x </li></ul></ul><ul><ul><li>C:WINNTsystem32driversetc </li></ul></ul><ul><ul><li>C:Windowssystem32driversetc </li></ul></ul><ul><li>The extension of the file is .SAM </li></ul><ul><li>Note: </li></ul><ul><ul><li>Store the file as “LMHOSTS” after modification with Notepad to avoid it being given a Notepad file extension </li></ul></ul>
  34. 34. Redirection to WINS <ul><li>If there are no entries in the LMHOSTS file, the request is redirected to a WINS server on the network </li></ul><ul><li>In the last example, there was no WINS server on the LAN </li></ul><ul><ul><li>Therefore, IE5 serarched for a web matching web address </li></ul></ul>
  35. 35. WINS Perspective of Name Resolution courses.ganesan.com InterNIC points to the DNS server At Pacbell Pacbell DNS server points to the DNS server at Ganesan.com DNS server at ganesan.com locates the host “course”
  36. 36. End of Module End of Chapter

×