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Could anyone explain the behavior of DNS slave?

I am testing DNS server, for internal purpose, and after configuring master slave everything works fine, but I am willing to understand the mechanism behind,

Lets say,
dnsmaster.net and dnsslave.net [my 2 DNS]

However, I wanted to make dnsslave to be available to serve query if dnsmaster.net is down. [well it works until now]

Having said that, I want to update records on dnsslave.net [while dnsmaster.net is down].
I can resolve things from DNS slave but turning off master and updating records, but not until I restart dnsslave.net.

So, is this something caused by, expiry time on soa?

                            43200      ; refresh (12 hours)
            900        ; retry (15 minutes)
            1209600    ; expire (2 weeks)
            300        ; minimum (5 minutes)

EDIT: I know what is the purpose of DNS master and slave, I am talking while dnsmaster is down, slave is only in use and I need to update A record. [at this condition DNS doesn't work with reload it only works on restart, so anyone with better knowledge and experience please share your view.]

Dave M
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tike
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    What? How are you changing records on the slave while the master is down? – faker Sep 16 '13 at 20:17
  • If you are using standard replication, then you shouldn't be editing a slave. DNS is a single master replication system. If the master is failed, you pick a new master and update settings so that it will be come the master. If you don't want that behavior, you have to use some external tool for replication, or a DNS server other then Bind. – Zoredache Sep 16 '13 at 20:34
  • well, that is the thing i am trying to solve, if dnsmaster is down, and i have only slave and assuming that i need to update A record. I will be updating slave. This is not an problem, and no wojciech you are wrong, you can update slave and treat it as master. I think answer are not what i am trying to know, i am willing to know what deny's slave not to serve until restart – tike Sep 16 '13 at 21:12

2 Answers2

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You cannot update a BIND slave by manually editing its zone file. Having said that, if you choose to use PowerDNS in a master-master setup, you can then edit the second server using PowerAdmin or manually editing the MySQL database (if database replication is configured).

Christopher H
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Slave nameserver updates its data from master by zone transfer. When master is down, slave can only serve what it transferred from master earlier.

grafzero
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