DNS主从复制图解

chinaux

此图是在网上看到的, 好像不错.


file:///C:/Documents%20and%20Settings/yajin/My%20Documents/dns-m-s.jpg

[ 本帖最后由 chinaux 于 2010-1-11 10:10 编辑 ]

llzqq

图画的不错，回头结合这个图写个文字说明文档

ruochen

原帖由 llzqq 于 2010-1-11 11:09 发表
图画的不错，回头结合这个图写个文字说明文档

期待
最近BZ的大作很不错

chinaux

这图不是我画的.

I try to share my understanding on zone transfer. Please correct me if wrong. Thanks.

Zone transfer happens when
I. the zone is updated on the master, and the master notifies the slave of the change.
II. the zone is reloaded on the slave.
II. the zone reaches "refresh" time on the slave.

Scenario I is demostrated by the diagram.   Usually it's triggered by a zone reload on the master.
1. notify. If the slave is configured in the "notify" list of a zone, then the slave is notified when the zone is updated on the master.
2. SOA query. The slave sends a SOA query to the master.
3. SOA answer.  The master returns the SOA answer to the slave.
4. check serial. The slave compares the serial number of the zone on the local host with the serial number in the SOA answer from the master.
5. AXFR/IXFR. If the serial number in the SOA answer is bigger, then a zone transfer request is sent to the master. AXFR: complete zone transfer request. IXFR: partial zone transfer request.
6. updated records. Updated zone data is transferred to the slave from the master.

Scenario II is kind of "rndc reload zone" on the slave.  The procedure of zone transfer is quite similar to the one of Scenario I,  but it has no Step 1 "notify".

The procedure of zone transfer in Scenario III is the same with the one in Scenario II. When the "refresh" time of the zone reaches, defined in its "SOA" record, the slave server starts Step 2 automatically, and then Step 3, 4, 5, 6.

[ 本帖最后由 chinaux 于 2010-1-12 09:52 编辑 ]