Optimizing DNS Configuration Method
Step 1 Configuring Redundant DNS Server Address
This can prevent the situation that the domain name cannot be resolved after the DNS Server single point of failure.
Take CentOS as an example:
Open the /etc/resolv.conf file on the host,
If only 1 IP is configured in the file, replace it with the following 2 IPs according to the following list:
| Data Center/Availability Zone | IP |
|---|---|
| Beijing Zone B | 10.9.255.1, 10.9.255.2 |
| Beijing Zone C | 10.10.255.1, 10.10.255.2 |
| Beijing Zone D | 10.19.255.1, 10.19.255.2 |
| Beijing Zone E | 10.42.255.1, 10.42.255.2 |
| Ulanqab Zone A | 100.65.128.2, 100.65.128.3 |
| Guangdong Zone B | 10.13.255.1, 10.13.255.2 |
| Hong Kong Zone A and B | 10.8.255.1, 10.8.255.2 |
| Los Angeles Zone A | 10.11.255.1, 10.11.255.2 |
| Singapore Zone B | 10.35.224.212, 10.35.250.52 |
| Singapore Zone A | 10.35.255.1, 10.35.255.2 |
| Bangkok, Thailand Zone A | 10.31.255.1, 10.31.255.2 |
| Washington Zone A | 10.27.255.1, 10.27.255.2 |
| Frankfurt, Germany Zone A | 10.29.255.1, 10.29.255.2 |
| Seoul, South Korea Zone A | 10.33.255.1, 10.33.255.2 |
| Moscow, Russia Zone A | 10.39.255.1, 10.39.255.2 |
| Tokyo, Japan Zone A | 10.40.255.1,10.40.255.2 |
| Taipei, Taiwan Zone A | 10.41.255.1,10.41.255.2 |
| Dubai, UAE Zone A | 10.44.255.1,10.44.255.2 |
| Jakarta, Indonesia Zone A | 10.45.255.1,10.45.255.2 |
| Mumbai, India Zone A | 10.47.255.1,10.47.255.2 |
| Sao Paulo, Brazil Zone A | 10.49.255.1,10.49.255.2 |
| London, UK Zone A | 10.50.255.1,10.50.255.2 |
| Manila Zone A | 100.64.48.2,100.64.48.3 |
| Bangkok, Thailand Zone B | 10.31.255.11,10.31.255.10 |
| Lagos Zone A | 10.52.255.1,10.52.255.2 |
| Ho Chi Minh, Vietnam Zone A | 100.64.0.2,100.64.0.3 |
| Shanghai Zone B | 10.23.255.1,10.23.255.2 |
Step 2 Enable NSCD Service
In Linux, turning on the NSCD service can locally cache the DNS resolution result. During the TTL time, there is no need to repeatedly resolve the DNS server, which speeds up the DNS resolution speed and alleviates the pressure on the DNS server.
Take CentOS as an example:
1、Install
yum install nscd2、Add configuration file /etc/nscd.conf
Content is as follows:
#
# /etc/nscd.conf
#
# An example Name Service Cache config file. This file is needed by nscd.
#
# Legal entries are:
#
# logfile <file>
# debug-level <level>
# threads <initial #threads to use>
# max-threads <maximum #threads to use>
# server-user <user to run server as instead of root>
# server-user is ignored if nscd is started with -S parameters
# stat-user <user who is allowed to request statistics>
# reload-count unlimited|<number>
# paranoia <yes|no>
# restart-interval <time in seconds>
#
# enable-cache <service> <yes|no>
# positive-time-to-live <service> <time in seconds>
# negative-time-to-live <service> <time in seconds>
# suggested-size <service> <prime number>
# check-files <service> <yes|no>
# persistent <service> <yes|no>
# shared <service> <yes|no>
# max-db-size <service> <number bytes>
# auto-propagate <service> <yes|no>
#
# Currently supported cache names (services): passwd, group, hosts, services
#
# logfile /var/log/nscd.log
threads 4
max-threads 32
server-user nscd
stat-user somebody
debug-level 5
reload-count 5
paranoia no
restart-interval 3600
enable-cache hosts yes
enable-cache passwd no
enable-cache group no
enable-cache services no
positive-time-to-live hosts 5
negative-time-to-live hosts 20
suggested-size hosts 211
check-files hosts yes
persistent hosts yes
shared hosts yes
max-db-size hosts 33554432
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### 3、Start service
service nscd start
### 4、Add to startup
chkconfig nscd on
### 5、If you need to stop the service
service nscd stop