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DNS Tutorial

kshounish5.bigleap.com IN A 192.192.192.5

kshounish5.bigleap.com IN A 192.192.192.6

kshounish7.bigleap.com IN A 192.192.192.7

kshounish8.bigleap.com IN A 192.192.192.8

kshounish9.bigleap.com IN A 192.192.192.9

kshounish10.bigleap.com IN A 192.192.192.10

DNS Database records

The database records used in zone file are called as standard resource records or sometimes, just “RRs”. All records have the same basic format:

Syntax Name In type data

In previous example

@ IN SOA kshounish2.love.com. root@kshounish2.love.com. (

2000011301 ; serial

3600 ; refresh

900 ; retry

1209600 ; expire

43200 ; default_ttl

)

can be described as follows

@: It means from the origin to the lastname object that is bigleap.com.

In: This stands for Internet servers

SOA: This stands for `Start Of Authority’. It marks the beginning of a zone’s data and defines the parameter that affects the entire zone. Followed by the current machine name where the DNS server is maintained. And, the administrator login, which can be used while DNS is not working.

20000011301;serial: This is the serial number--a numeric value that tells or notifies the slave server, that the database has been updated. So slave server should also update it.

3600;refresh: This is the refresh cycle in seconds. In every refresh cycle the slave server comes to master server and checks for the updated database.

1800;retry: This particular line refers to the retry cycle which in turn means that the slave server should wait before asking the master server again in case master server doesn’t respond.

1209600;expire: This is the time for slave server to respond to queries of client for the expiration time if master server fails and has to be up and not getting up. After this period slave server also fails to solve the queries of clients and sits idle.

432100;default_ttl: This refers to the default time to leave, for this domain to work for, when named is once started. Remember the user doesn’t have to play with this unless he wants that the query time from the slave server should be somewhat less or more. In case we want to change, we should change only the refresh time in both master and slave. The best way is to make it 2, which means after each 2 seconds slave server will query to master server.