SGS-6341-Series User Manual
Table Of Contents
- Chapter 1 INTRODUCTION
- Chapter 2 INSTALLATION
- Chapter 3 Switch Management
- Chapter 4 Basic Switch Configuration
- Chapter 5 File System Operations
- Chapter 6 Cluster Configuration
- Chapter 7 Port Configuration
- Chapter 8 Port Isolation Function Configuration
- Chapter 9 Port Loopback Detection Function Configuration
- Chapter 10 ULDP Function Configuration
- Chapter 11 LLDP Function Operation Configuration
- Chapter 12 Port Channel Configuration
- Chapter 13 MTU Configuration
- Chapter 14 EFM OAM Configuration
- Chapter 15 PORT SECURITY
- Chapter 16 DDM Configuration
- Chapter 17 LLDP-MED
- Chapter 18 bpdu-tunnel Configuration
- Chapter 19 EEE Energy-saving Configuration
- Chapter 20 VLAN Configuration
- Chapter 21 MAC Table Configuration
- Chapter 22 MSTP Configuration
- Chapter 23 QoS Configuration
- Chapter 24 Flow-based Redirection
- Chapter 25 Flexible Q-in-Q Configuration
- Chapter 26 Layer 3 Management Configuration
- Chapter 27 ARP Scanning Prevention Function Configuration
- Chapter 28 Prevent ARP Spoofing Configuration
- Chapter 29 ARP GUARD Configuration
- Chapter 30 Gratuitous ARP Configuration
- Chapter 31 DHCP Configuration
- Chapter 32 DHCPv6 Configuration
- Chapter 33 DHCP Option 82 Configuration
- Chapter 34 DHCP Option 60 and option 43
- Chapter 35 DHCPv6 Options 37, 38
- Chapter 36 DHCP Snooping Configuration
- Chapter 37 DHCP Snooping Option 82 Configuration
- Chapter 38 IPv4 Multicast Protocol
- Chapter 39 IPv6 Multicast Protocol
- Chapter 40 Multicast VLAN
- Chapter 41 ACL Configuration
- Chapter 42 802.1x Configuration
- 42.1 Introduction to 802.1x
- 42.2 802.1x Configuration Task List
- 42.3 802.1x Application Example
- 42.4 802.1x Troubleshooting
- Chapter 43 The Number Limitation Function of MAC and IP in Port, VLAN Configuration
- Chapter 44 Operational Configuration of AM Function
- Chapter 45 Security Feature Configuration
- 45.1 Introduction to Security Feature
- 45.2 Security Feature Configuration
- 45.2.1 Prevent IP Spoofing Function Configuration Task Sequence
- 45.2.2 Prevent TCP Unauthorized Label Attack Function Configuration Task Sequence
- 45.2.3 Anti Port Cheat Function Configuration Task Sequence
- 45.2.4 Prevent TCP Fragment Attack Function Configuration Task Sequence
- 45.2.5 Prevent ICMP Fragment Attack Function Configuration Task Sequence
- 45.3 Security Feature Example
- Chapter 46 TACACS+ Configuration
- Chapter 47 RADIUS Configuration
- Chapter 48 SSL Configuration
- Chapter 49 IPv6 Security RA Configuration
- Chapter 50 MAB Configuration
- Chapter 51 PPPoE Intermediate Agent Configuration
- Chapter 52 Web Portal Configuration
- Chapter 53 VLAN-ACL Configuration
- Chapter 54 SAVI Configuration
- Chapter 55 MRPP Configuration
- Chapter 56 ULPP Configuration
- Chapter 57 ULSM Configuration
- Chapter 58 Mirror Configuration
- Chapter 59 sFlow Configuration
- Chapter 60 RSPAN Configuration
- Chapter 61 ERSPAN
- Chapter 62 SNTP Configuration
- Chapter 63 NTP Function Configuration
- Chapter 64 Summer Time Configuration
- Chapter 65 DNSv4/v6 Configuration
- Chapter 66 Monitor and Debug
- Chapter 67 Reload Switch after Specified Time
- Chapter 68 Debugging and Diagnosis for Packets Received and Sent by CPU
- Chapter 69 Dying Gasp Configuration
- Chapter 70 PoE Configuration
65-57
Chapter 65 DNSv4/v6 Configuration
65.1 Introduction to DNS
DNS (Domain Name System) is a distributed database used by TCP/IP applications to translate domain
names into corresponding IPv4/IPv6 addresses. With DNS, you can use easy-to-remember and signification
domain names in some applications and let the DNS server translate them into correct IPv4/IPv6 addresses.
There are two types of DNS services, static and dynamic, which supplement each other in application. Each
time the DNS server receives a name query it checks its static DNS database first before looking up the
dynamic DNS database. Some frequently used addresses can be put in the static DNS database, the
reduction the searching time in the dynamic DNS database would increase efficiency. The static domain name
resolution means setting up mappings between domain names and IPv4/IPv6 addresses. IPv4/IPv6
addresses of the corresponding domain names can be found in the static DNS database when you use some
applications. Dynamic domain name resolution is implemented by querying the DNS server. A user program
sends a name query to the resolver in the DNS client when users want to use some applications with domain
name, the DNS resolver looks up the local domain name cache for a match. If a match is found, it sends the
corresponding IPv4/IPv6 address back to the switch. If no match is found, it sends a query to a higher DNS
server. This process continues until a result, whether success or failure, is returned.
The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource
participating in the Internet. It associates various information with domain names assigned to such
participants. Most importantly, it translates humanly meaningful domain names to the numerical (binary)
identifiers associated with networking equipment for the purpose of locating and addressing these devices
world-wide. An often used analogy to explain the Domain Name System is that it serves as the "phone book"
for the Internet by translating human-friendly computer hostnames into IP addresses.
The Domain Name System makes it possible to assign domain names to groups of Internet users in a
meaningful way, independent of each user's physical location. Because of this, World-Wide Web (WWW)
hyperlinks and Internet contact information can remain consistent and constant even if the current Internet
routing arrangements change or the participant uses a mobile device. Internet domain names are easier to
remember than IP addresses such as 208.77.188.166(IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6).
People take advantage of this when they recite meaningful URLs and e-mail addresses without having to
know how the machine will actually locate them.
The Domain Name System distributes the responsibility for assigning domain names and mapping them to
Internet Protocol (IP) networks by designating authoritative name servers for each domain to keep track of
their own changes, avoiding the need for a central register to be continually consulted and updated.
In general, the Domain Name System also stores other types of information, such as the list of mail servers
that accept email for a given Internet domain. By providing a world-wide, distributed keyword-based
redirection service, the Domain Name System is an essential component of the functionality of the Internet.
User’s Manual of SGS-6341 series