A domain level name server may contain a list of DNS servers where a name record is kept. It then informs the resolver of the IP address(es) or location of these DNS servers. The resolver then attempts to query the ADNS servers. It attempts to resolve against the first server (ns1.x.x.x.x), if query fails then it attempts the to query the second (ns2.x.x.x.x) and so forth.
A DNS server may contain multiple addresses for a domain name. When requests are made to the DNS server from the resolver, the server shuffles the multiple IP addresses associated with the domain name then selects one to return to the client.
A name record is constant in a DNS server. For example, if a web server hosting domain www.mywebserver.com which a name record points to is no longer available the name record will continue to point to that server. A GTM device is useful in monitoring servers in a redundant setup and returning an IP address associated with a server which is reachable.
References:
http://support.f5.com/kb/en-us/solutions/public/9000/600/sol9619.html
http://www.wight-hat.com/guides/hosting/round-robin-dns-configuration/
http://support.citrix.com/article/CTX122619
http://www.networkcomputing.com/wan-optimization-and-application-acceleration/a-gslb-reality-check.php
http://support.f5.com/kb/en-us/solutions/public/0000/100/sol159.html
No comments:
Post a Comment