HOWTO - Configure Round Robin and Load Balancing. This HOWTO assumes you want the DNS server to respond with different IP addresses (or change the order of a given set of addresses) in order to provide a simple load balancing solution. You have a choice of solutions depending on what you want to do: Contents Balancing Mail Balancing Other Services Balancing Services using SRV Balancing Services using Split-Horizons Controlling the Round Robin Effectiveness of DNS Load Balancing Balancing Mail The normal method of handling mail fail-over is using the 'preference' value which is described in this note .
Define multiple MX records with the same priority, for example: ; zone file fragment IN MX 10 mail.example.com. In all the above cases each mail server must be capable of handling and synchronising the load for all the mail boxes served by the domain, either using some appropriate back-end to do this or by defining all but one server to be a relay or forwarder. Balancing Other Services Balancing Services Balancing Services with Split-Horizon. Server Load Balancing Methods - WebsiteGear. Server Load Balancing Methods Published: Tuesday, May 18, 2004 Methods of load balancing There are various ways in which load balancing can be achieved.
The deciding factors for choosing one over the other depends on the requirement, available features, complexity of implementation, and cost. For example, using a hardware load balancing equipment is very costly compared to the software version. Round Robin DNS Load BalancingThe in-built round-robin feature of BIND of a DNS server can be used to load balance multiple web servers. Round Robin DNS Load Balancing - WebsiteGear. Round Robin DNS Load Balancing Published: Thursday, May 20, 2004 How DNS load balancing works When the request comes to the DNS server to resolve the domain name, it gives out one of the several canonical names in a rotated order. This redirects the request to one of the several servers in a server group. Once the BIND feature of DNS resolves the domain to one of the servers, subsequent requests from the same client are sent to the same server. DNS load balancing implementation (Multiple CNAMES) This approach works for BIND 4 name servers, where multiple CNAMES are not considered as a configuration error.
Srv1 IN A 123.45.67.1srv2 IN A 123.45.67.2srv3 IN A 123.45.67.3srv4 IN A 123.45.67.4 Add the following canonical names to resolve www.domain.com to one of these servers. www IN CNAME srv1.domain.tld. The DNS server will resolve the www.domain.com to one of the listed servers in a rotated manner. Options { multiple-cnames yes;}; DNS load balancing implementation (Multiple A Records) HOWTO - Configure Round Robin and Load Balancing. This HOWTO assumes you want the DNS server to respond with different IP addresses (or change the order of a given set of addresses) in order to provide a simple load balancing solution.
You have a choice of solutions depending on what you want to do: Contents Balancing Mail The normal method of handling mail fail-over is using the 'preference' value which is described in this note. However, using the MX record you can balance mail in two ways. Define multiple MX records with the same priority, for example: ; zone file fragment IN MX 10 mail.example.com. In all the above cases each mail server must be capable of handling and synchronising the load for all the mail boxes served by the domain, either using some appropriate back-end, access to a common file system (NAS, NFS etc.) or by defining all but one server to be a mail relay or forwarder. Balancing Other Services Note: While above example shows IPv4 addresses using A RRs, the principle applies equally to IPv6 addresses using AAAA RRs.
DNS BIND Query Statements. This chapter describes all the statements available in BIND 9.x relating to or controlling queries. Full list of named.conf statements. additional-from-auth, additional-from-cache additional-from-auth yes | no ; additional-from-cache yes | no ; additional-from-auth and additional-from-cache control the behaviour when zones have additional (out-of-zone) data or when following CNAME or DNAME records.
These options are for used for configuring authoritative-only (non-caching) servers and are only effective if recursion no is specified in a global options clause or in a view clause. The default in both cases is yes. These statements may be used in a global options or in a view clause. Prior to BIND 9.5 auth-from-cache also controlled whether a recursive query (even when recursion no; was specified) would return a referral to the root servers (since these would, most likely, be available in the cache). Allow-query, allow-query-on allow-query-cache, allow-query-cache-on auth-nxdomain blackhole.