76
DNS C
ONFIGURATION
DNS Overview
Domain name system (DNS) is a distributed database system that provides domain
name-to-IP address mappings for TCP/IP applications. With DNS, users using IP
applications can directly use meaningful easy-to-remember domain names, which
will be resolved and mapped to corresponding IP addresses by DNS servers.
There are two types of DNS resolution, “Static DNS Resolution” on page 831 and
“Dynamic DNS Resolution” on page 831. When a name query is received, the
static resolution is first performed to check the static DNS list. If the static
resolution fails, the dynamic resolution is performed. Because dynamic resolution
needs the participating of DNS server and may spend some time, you can put
some commonly used domain names in the static DNS list to increase the
resolution efficiency.
Static DNS Resolution
With static DNS resolution, you can manually configure some name-to-address
mappings in the static DNS list, and the system will search the static list for
corresponding IP addresses when users use domain names with some applications
(such as telnet).
Dynamic DNS Resolution
Resolving procedure
The procedure of dynamic DNS resolution is as follows:
1
A user program sends a name query to the resolver in the DNS Client.
2
The DNS resolver looks up the local DNS cache for a match. If a match is found, it
returns the corresponding IP address to the user program. If not, it sends a query
to the DNS Server.
3
The DNS Server looks up its database for a match. If no match is found, it sends a
query to its parent DNS Server. If the parent DNS Server does not have the
information, it sends the query to another server. This process continues until a
result (either successful or failed) is found. Finally, the resolution result is returned
to the DNS Client.
4
The DNS Client performs the next operation according to the result.
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Страница 70: ...70 CHAPTER 5 LOGGING IN USING MODEM ...
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Страница 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT ...
Страница 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION ...
Страница 126: ...126 CHAPTER 14 SUPER VLAN ...
Страница 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION ...
Страница 152: ...152 CHAPTER 17 IPX CONFIGURATION ...
Страница 164: ...164 CHAPTER 19 QINQ CONFIGURATION ...
Страница 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION ...
Страница 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION ...
Страница 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION ...
Страница 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION ...
Страница 224: ...224 CHAPTER 27 DLDP CONFIGURATION ...
Страница 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT ...
Страница 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION ...
Страница 280: ...280 CHAPTER 30 MSTP CONFIGURATION ...
Страница 348: ...348 CHAPTER 35 IS IS CONFIGURATION ...
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Страница 412: ...412 CHAPTER 40 HABP CONFIGURATION ...
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Страница 426: ...426 CHAPTER 42 GMRP CONFIGURATION ...
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Страница 506: ...506 CHAPTER 48 MSDP CONFIGURATION ...
Страница 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION ...
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Страница 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200 ...
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Страница 684: ...684 CHAPTER 61 QOS CONFIGURATION ...
Страница 718: ...718 CHAPTER 63 CLUSTER ...
Страница 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION ...
Страница 752: ...752 CHAPTER 69 RMON CONFIGURATION ...
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Страница 814: ...814 CHAPTER 74 FTP AND TFTP CONFIGURATION ...
Страница 830: ...830 CHAPTER 75 INFORMATION CENTER ...
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Страница 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING ...
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