1. Ersin KARA Istanbul Kültür Üniversitesi Bilgisayar Mühendisliği III
Ersin KARA Istanbul Kültür Üniversitesi Bilgisayar Mühendisliği III.Sınıf

2. Configuring a Client for Name Resolution

3. Resolving Names

4. Resolving Host Names by Using Domain Name System (DNS)

5. The Name Resolution Process
A DNS client can use several different methods to resolve an IP address from an FQDN
DNS Server
Payroll.contoso.msft
Corp01.contoso.msft

6. The Types of Names Computers Use
Description
NetBIOS Names
16-byte address
Can represent a single computer or group of computers
15 characters used for the name
16th character is used by the services that a computer offers to the network
Host Names
Assigned to a computer’s IP address
255 characters in length
Can contain alphabetic and numeric characters, hyphens, and periods.
Can take various forms
Alias
Domain name

7. What is the IP address for s1?
Using a Hosts File
What is the IP address for s1? 1
localhost
router
server1.central.microsoft.com s1
Hosts File 2
Client

8. Using Dynamic Name Resolution
What Is WINS?
What Is DNS?
The DNS Suffix

9. What Is WINS? ? 1 2 3 OK Queries a WINS Server
Payroll
WINS Server
NetBIOS Name
Registration Query OK ?
Queries a WINS Server
Determines if name is in use or not
If not in use, then registers the NetBIOS name and associated IP address 1 2 3

10. FQDN: printserver.contoso.com. Other top-level domains
What Is DNS?
FQDN: printserver.contoso.com.
Root domain
( “.” Root)
Other top-level domains
Com
Parent domain
Edu
Org
Contoso
Child domain
printserver
accounts
payroll

11. The DNS Suffix corp05.contoso.com. corp01.sales.contoso.com. “.” Root
FQDN
corp05.contoso.com.
corp01.sales.contoso.com.
DNS Suffix
Host Name
corp01 =
corp05 =
com
“.” Root
contoso
sales

12. How Client Names Are Resolved
Enter command 1
Name is resolved
Lmhosts File 8
DNS name cache 2
Broadcast 7
WINS Server 6
Hosts File 3
DNS Server 4
NetBIOS name cache 5

13. How Names Are Mapped to IP Addresses
Name Resolution
Service
Computer44
Where is the Computer44 file? 1 2 3

14. server1.training.nwtraders.msft.
What Are Host Names?
A host name is the DNS name, of a device on a network, that is used to locate computers on the network
Examples:
Server1 =
Server1 =
msft
“.” Root
nwtraders
training
FQDN
server1.nwtraders.msft.
server1.training.nwtraders.msft.
DNS Suffix
Host Name

15. What Are NetBIOS Names?
A NetBIOS name is an identifier used by NetBIOS services running on a computer. It is made up of a 15-character name plus a 16th character (byte) denoting the service
NetBIOS Name
16th character
Services
IP address
Server2 00
Workstation 20
Server 01
Messenger
Server2

16. Configuring Host Name Resolution
The Host Name Resolution Process
Client Resolver Cache
How to View and Flush the Client Resolver Cache
Hosts File
How to Preload the Client Resolver Cache by Using a Hosts File

17. The Host Name Resolution Process
Client Resolver Cache/Hosts File
NetBIOS
Name Cache
DNS
WINS
Broadcast
Lmhost File 2 1
Salescomputer2
What is the
IP address for Salescomputer2? 3
Salescomputer2
Host name resolution is the process of resolving a host name to an IP address

18. Client Resolver Cache
The client resolver cache is a location in memory that stores host names that have recently been resolved to IP addresses. It also stores host name-to-IP address mappings loaded from the Hosts file
Computer1
Resolved host names
from the DNS server
Hosts File

19. Hosts File
The Hosts file is a static file that is maintained on the local computer and that is used to load host name-to-IP address mappings into the client resolver cache
# Copyright (c) Microsoft Corp. #
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
# For example:
#           rhino.acme.com         # source server
#            x.acme.com               # x client host
       localhost
Computer1
Hosts File

20. Overview of Domain Name System
Domain Name System (DNS) is a hierarchical, distributed database that contains mappings of DNS domain names to various types of data, such as IP addresses
DNS is the foundation of the Internet naming scheme and the foundation of an organization’s naming scheme
DNS supports accessing resources by using alphanumeric names
InterNIC is responsible for delegating administrative responsibility for portions of the domain namespace and for registering domain names
DNS was designed to solve issues that arose when there was an increase in the:
Number of hosts on the Internet
Traffic generated by the update process
Size of the Hosts file

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

22. 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

23. What Are the Components of a DNS Solution?
DNS Servers on the Internet
DNS Servers
DNS Clients
Root “.”
.com
.edu
Resource
Record

24. What Is a DNS Query?
A query is a request for name resolution to a DNS server. There are two types of queries: recursive and iterative
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

25. How Recursive Queries Work
A recursive query is a query made to a DNS server, in which the DNS client asks the DNS server to provide a complete answer to the query
DNS server checks the forward lookup zone and cache for an answer to the query
Computer1
Recursive query for
mail1.nwtraders.com
Database
Local DNS Server

26. How Root Hint Works
Root hints are DNS resource records stored on a DNS server that list the IP addresses for the DNS root servers
Cluster of
DNS Servers
Cluster of
Root (.) Servers
Root Hints
com
DNS Server
microsoft
Computer1

27. How Iterative Queries Work
An iterative query is a query made to a DNS server in which the DNS client requests the best answer that the DNS server can provide without seeking further help from other DNS servers. The result of an iterative query is often a referral to another DNS server lower in the DNS tree
Iterative Query
Local
DNS Server
Root Hint (.)
Ask .com 1
Iterative Query
.com
Ask nwtraders.com
Recursive query for
mail1.nwtraders.com 2
Iterative Query
Authoritative Response 3
Computer1
nwtraders.com

28. Authoritative Response
How Forwarders Work
A forwarder is a DNS server designated by other internal DNS servers to forward queries for resolving external or offsite DNS domain names
Iterative Query
Forwarder
Root Hint (.)
Ask .com
Iterative Query
.com
Ask nwtraders.com
Recursive Query
Iterative Query
Authoritative Response
Recursive query for
mail1.nwtraders.com
nwtraders.com
Local
DNS Server
Computer1

29. How DNS Server Caching Works
Caching Table
Host Name
IP Address
TTL
clientA.contoso.msft.
28 seconds
ClientA is at
Where’s Client A?
ClientA
Client1
Where’s Client A?
ClientA is at
Client2
Caching is the process of temporarily storing recently accessed information in a special memory subsystem for quicker access

30. Configuring DNS Zones How DNS Data Is Stored and Maintained
What Are Resource Records and Record Types?
What Is a DNS Zone?
What Are DNS Zone Types?
How to Change a DNS Zone Type
What Are Forward and Reverse Lookup Zones?
How to Configure Forward and Reverse Lookup Zones

31. How DNS Data Is Stored and Maintained
Namespace: training.nwtraders.msft
DNS Server
Resource records for the zone training.nwtraders.msft
Host name
IP address
DNS ClientA
DNS ClientB
DNS ClientC
Zone File:
Training.nwtraders.msft.dns
DNS ClientC
DNS ClientA
DNS ClientB
A resource record (RR) is a standard DNS database structure containing information used to process DNS queries
A zone is a portion of the DNS database that contains the resource records with the owner names that belong to the contiguous portion of the DNS namespace

32. What Are Resource Records and Record Types?
Description A
Resolves a host name to an IP address
PTR
Resolves an IP address to a host name
SOA
The first record in any zone file
SRV
Resolves names of servers providing services NS
Identifies the DNS server for each zone MX
The mail server
CNAME
Resolves from a host name to a host name

33. What Is a DNS Zone?
Nwtraders
West
South
Support
Sales
Training
North

34. What Are DNS Zone Types? Zones Description 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

35. What Are Forward and Reverse Lookup Zones?
Namespace: training.nwtraders.msft.
Forward zone
Training
DNS Client1
DNS Client2
DNS Client3
Reverse zone
in-addr.arpa
DNS Server Authorized
for training
DNS Client2 = ?
= ?
DNS Client3
DNS Client1
DNS Client2

36. Configuring DNS Zone Transfers
How DNS Zone Transfers Work
How DNS Notify Works
How to Configure DNS Zone Transfers

37. How DNS Zone Transfers Work
A DNS zone transfer is the synchronization of authoritative DNS zone data between DNS servers 1
SOA query for a zone 2
SOA query answered 3
IXFR or AXFR query for a zone
IXFR or AXFR query answered
(zone transfer) 4
Secondary Server
Primary and
Master Server

38. How DNS Notify Works
A DNS notify is an update to the original DNS protocol specification that permits notification to secondary servers when zone changes occur
Resource record is updated 1
Destination Server
Source Server
SOA serial number is updated 2 3
DNS notify
Zone transfer 4
Secondary Server
Primary and
Master Server

39. What Are Dynamic Updates?
A dynamic update is the process of a DNS client dynamically creating, registering, or updating its records in zones that are maintained by DNS servers that can accept and process messages for dynamic updates
A manual update is the process of an administrator manually creating, registering, or updating the resource record
Dynamic update enables DNS client computers to interact automatically with the DNS server to register and update their own resource records
Organizations that have dynamic changes can benefit from the dynamic method of updating DNS resource records
Organizations may benefit from manual update if they:
Are in a smaller environment that has few changes to their resource records
Have isolated instances, such as when a larger organization chooses to control every address on every host.

40. How DNS Clients Register and Update Their Own Resource Records by Using Dynamic Updates
DNS Server
Client sends SOA query 1
DNS server sends zone name and server IP address 2 1 2 3 4 5 3
Client verifies existing registration
DNS server responds by stating that registration does not exist 4
Client sends dynamic update to DNS server 5
Windows
Server 2003
Windows XP
Windows
2000

41. How a DHCP Server Registers and Updates Resource Records by Using Dynamic Updates
DNS Server
DHCP client makes an IP lease request
DHCP server grants IP lease
DHCP server automatically generates client’s FQDN
Using dynamic update, the DHCP server updates the DNS forward and reverse records for the client 1 2 3 4
Resource
Records 3 4 1 2
Window Server 2003
Running DHCP
IP Address Lease
DHCP Down-
level Client

42. What Is an Active Directory-Integrated DNS Zone?
DNS zone type
Benefit
Non Active Directory-integrated zone
Does not require Active Directory
Active Directory-integrated zone
Stores DNS zone data in Active Directory and is thus more secure
Uses Active Directory replication instead of zone transfers
Allows only secure dynamic updates
Uses multi-master instead of single master structure
An Active Directory-integrated DNS zone is a DNS zone stored in Active Directory

43. How Active Directory-Integrated DNS Zones Use Secure Dynamic Updates
A secure dynamic update is a process in which a client submits a dynamic update request to a DNS server, and the server attempts the update only if the client can prove its identity and has the proper credentials to make the update
Find authoritative server
DNS Client
running
Windows XP
Local
DNS Server
Result
Find authoritative server
Result
Attempt non-secure update
Refused
Secure update negotiation
Accepted
Domain Controller with
Active Directory-
Integrated DNS Zone

44. Configuring a DNS Client
How Preferred and Alternate DNS Servers Work
How Suffixes Are Applied
How to Configure a DNS Client

45. How Preferred and Alternate DNS Servers Work
3. Optionally, you can enter a whole list of alternate DNS servers
1. The preferred DNS server is the one that the client tries first
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
2. If the preferred server fails, the client tries the alternate DNS server

46. How Suffixes Are Applied
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

47. Delegating Authority for Zones
What Is Delegation of a DNS Zone?
How to Delegate a Subdomain to a DNS Zone

48. What Is Delegation of a DNS Zone?
Namespace: training.nwtraders.msft
DNS server
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
training.nwtraders.msft
Training.nwtraders.com now has its own administrator and DNS server to resolve queries in that part of the namespace/organization
DNS server
training.nwtraders.msft
Delegation is the process of assigning authority over child domains in your DNS namespace to another entity by adding records in the DNS database

49. Managing and Monitoring Domain Name System (DNS)

50. Overview Configuring the Time-to-Live Value
Configuring Aging and Scavenging
Integrating DNS with WINS
Testing the DNS Server Configuration
Verifying that a Resource Record Exists by Using Nslookup, DNSCmd, and DNSLint
Monitoring DNS Server Performance

51. Configuring the Time-to-Live Value
How the Time-to-Live Value Works
How to Configure the Time-to-Live Value

52. How the Time-to-Live Value Works
The Time-to-Live (TTL) value is a time-out value expressed in seconds that is included with DNS records that are returned in a DNS query 
Resource Record
Resource Record
Cache
Cache
Zone
Authoritative
DNS Server2
DNS Client
DNS Server1
TTL set
on the zone
The records in the zone are sent to other DNS servers and clients in response to queries 1
DNS servers and DNS clients that store the record in their cache hold the record for the TTL period supplied in the record 2
When the TTL expires, the record is removed from the cache 3

53. How to Configure the Time-to-Live Value
Your instructor will demonstrate how to:
Adjust the TTL value for a zone
Adjust the TTL value for a resource record

54. Configuring Aging and Scavenging
What Are Aging and Scavenging Parameters?
How Aging and Scavenging Work
How to Configure Aging and Scavenging

55. What Are Aging and Scavenging Parameters?
Aging is the process that determines whether a stale DNS resource record should be removed from the DNS database  
Scavenging is the process of cleaning and removing outdated or extinct names data from the WINS database
A refresh attempt is the process of a computer requesting a refresh on its DNS record
Parameter
Description
Example
No Refresh Interval
The time period when the DNS server does not accept refresh attempts
7-days (default)
Refresh Interval
The time period when the DNS server does accept refresh attempts

56. How Aging and Scavenging Works
7-days
7-days
Jan 1
Jan 8
Jan 15
Time
stamped
No-Refresh
interval
Refresh
interval
Scavenge
Aging

57. How to Configure Aging and Scavenging
Your instructor will demonstrate how to:
Set aging/scavenging parameters for the DNS server
Set aging/scavenging parameters on a DNS zone
Enable automatic scavenging of stale resource records on a DNS server
Start immediate scavenging of stale resource records
View when a zone can start scavenging stale resource records
Configure the time stamp on a DNS resource record
View the time stamp on a dynamic resource record

58. Integrating DNS and WINS
Multimedia: DNS and WINS Integration
How to Integrate DNS with WINS

59. DNS and WINS Integration
The objective of this presentation is to explain how DNS and WINS can be integrated in the network infrastructure
At the end of this presentation, you will be able to:
Define DNS and WINS integration
Explain how host names and NetBIOS names fit into DNS and WINS integration
Describe how DNS and WINS integration works

60. Testing the DNS Server Configuration
How Simple and Recursive Queries Work
How to Test the DNS Server Configuration

61. How Simple and Recursive Queries Work
A simple query is a query that performs a local test by using the DNS client to query the DNS server
A recursive query is a query that tests a DNS server by forwarding a recursive query to another DNS server
DNS Server
DNS Root Server
DNS Service
Authoritative zone:
training.nwtraders.msft
DNS Client Resolver

62. Verifying that a Resource Record Exists by Using Nslookup, DNSCmd, and DNSLint
Why Verify that a Resource Record Exists?
Nslookup
DNSCmd
DNSLint
How to Verify that a Resource Record Exists by Using Nslookup, DNSCmd, and DNSLint

63. Why Verify that a Resource Record Exists?
To identify issues with your DNS solution, you can verify:
Missing records
Incomplete records
Incorrectly configured records
You can use the following three utilities to monitor DNS:
Nslookup
DNSCmd
DNSLint

64. Nslookup
Nslookup is a command-line utility used to diagnose DNS infrastructure

65. DNSCmd
DNSCmd is a DNS support tool which allows you to complete many DNS administrative tasks on the DNS server from a command prompt

66. DNSLint
DNSLint is a Microsoft Windows utility that can run a series of queries to help diagnose common DNS name resolution issues

67. Monitoring DNS Server Performance
Guidelines for Monitoring DNS Server Performance by Using the Performance Console
What Is a DNS Event Log?
What Is DNS Debug Logging?
How to Monitor DNS Server Performance by Using Logging

68. Monitoring DNS Server Performance
Guidelines for Monitoring DNS Server Performance by Using the Performance Console
What Is a DNS Event Log?
What Is DNS Debug Logging?
How to Monitor DNS Server Performance by Using Logging

69. Guidelines for Monitoring DNS Server Performance by Using the Performance Console
Performance counter
What to look for after a baseline is established
Dynamic Update Rejected
Any increase over the baseline may be cause for further investigation
Recursive Queries/sec
If this counter goes dramatically up or down, then it should be further investigated
AXFR Request Sent
If this counter goes dramatically above the baseline, then it could reflect a need to review the number of changes in the zone and the configuration of zone transfers

70. What Is a DNS Event Log?
A DNS event log is a system log configured to log only DNS events

71. What Is DNS Debug Logging?
DNS debug logging is an optional logging tool for DNS that stores the DNS information that you select
Primary DNS Server1
Secondary DNS Server2

72. Questions