Bind9 slave not updating
If they don’t have info about such requested query they will pass the request to the Top Level domain (TLD), if TLD say I don’t know the request, may be the authoritative server know your request, it will forward to authoritative servers, here only defined as address .56.In mean time authoritative server will give the answer to TLD and TLD will pass to root server and root will provide the info to browser, hence the browser will cache the DNS request for future use.Feature: Automatically increase SOA serial number when a DNS zone managed by Identity Management any record in the zone is updated.This feature takes advantage of and requires persistent search data refresh mechanism, which is enabled by default in the Identity Management server install script.In this way, DNS alleviates the need to remember IP addresses. Ubuntu ships with BIND (Berkley Internet Naming Daemon), the most widely deployed DNS server.
The Domain Name System makes it possible to assign domain names to groups of Internet resources and users in a meaningful way, independent of each entity's physical location.
You need to place following two directives in options section of on each slave server: The transfer-source and transfer-source-v6 clauses specify the IPv4 and IPv6 source address to be used for zone transfer with the remote server, respectively.
Also, you need set use-alt-transfer-source to yes so that the alternate transfer sources can be used.
Domain Name Server (DNS) used for name resolving to any hosts.
Master DNS servers (Primary Server) are the original zone data handlers and Slave DNS server (Secondary Server) are just a backup servers which is used to copy the same zone information’s from the master servers.