Canonical name (CNAME) handling for global server load balancing
First Claim
1. A method of providing load balancing in a network, the method comprising:
- receiving, by a processor, a domain name system (DNS) reply to a DNS request to resolve an alias host name that is an alias for a primary domain, wherein the DNS reply includesa canonical name (CNAME) record identifying the primary domain, andnetwork addresses that correspond with the primary domain;
detecting, by said processor, the CNAME record identifying the primary domain in said DNS reply;
applying, by said processor a load balancing algorithm configured to be applied to DNS requests for the primary domain to the network addresses received in response to the DNS request to resolve the alias host name; and
sending, by said processor, to a client program that originated the DNS request to resolve the alias host name, a response to the DNS request that includes a list of the network addresses associated with the primary domain that has been ordered according to the load balancing algorithm configured to be applied to DNS requests for the primary domain.
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Abstract
Canonical name (CNAME) handling is performed in a system configured for global server load balancing (GSLB), which orders IP addresses into a list based on a set of performance metrics. When the GSLB switch receives a reply from an authoritative DNS server, the GSLB switch scans the reply for CNAME records. If a CNAME record is detected and it points to a host name configured for GSLB, then a GSLB algorithm is applied to the reply. This involves identifying the host name (pointed to by the CNAME record) in the reply and applying the metrics to the list of returned IP addresses corresponding to that host name, to reorder the list to place the “best” IP address at the top. If the CNAME record in the reply points to a host name that is not configured for GSLB, then the GSLB sends the reply unaltered to the inquiring client.
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Citations
18 Claims
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1. A method of providing load balancing in a network, the method comprising:
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receiving, by a processor, a domain name system (DNS) reply to a DNS request to resolve an alias host name that is an alias for a primary domain, wherein the DNS reply includes a canonical name (CNAME) record identifying the primary domain, and network addresses that correspond with the primary domain; detecting, by said processor, the CNAME record identifying the primary domain in said DNS reply; applying, by said processor a load balancing algorithm configured to be applied to DNS requests for the primary domain to the network addresses received in response to the DNS request to resolve the alias host name; and sending, by said processor, to a client program that originated the DNS request to resolve the alias host name, a response to the DNS request that includes a list of the network addresses associated with the primary domain that has been ordered according to the load balancing algorithm configured to be applied to DNS requests for the primary domain. - View Dependent Claims (2, 3, 10, 18)
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4. An article of manufacture, comprising:
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a non-transitory storage medium having instructions stored thereon that are executable by a computing device to; receive, by said computing device, a domain name system (DNS) reply for an alias associated with a canonical name (CNAME) record, wherein the alias is for a primary domain; detect, by said computing device, the CNAME record in said DNS reply identifying the primary domain; and apply, by said computing device a load balancing algorithm configured to be applied to DNS requests for the primary domain, to a list of one or more network addresses provided in the DNS reply for the alias. - View Dependent Claims (5, 6, 11)
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7. An apparatus to provide load balancing, the apparatus comprising:
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a network device to load balance configurable as a proxy to an authoritative domain name system (DNS) server and including; a non-transitory storage medium having instructions stored thereon; a parser to receive a DNS reply and to detect the CNAME record in said DNS reply, wherein said DNS reply was generated by the authoritative DNS server in response to a DNS query to resolve an alias into network addresses, the alias associated with a canonical name (CNAME) record, wherein the alias is for a primary domain; and a controller coupled to the parser, the controller being operative to apply a load balancing algorithm for the primary domain, to a list of one or more network addresses provided in the DNS reply to the DNS query to resolve the alias into network addresses. - View Dependent Claims (8, 9)
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12. An apparatus to provide load balancing, the apparatus comprising:
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a network device to load balance configured to; receive a domain name system (DNS) reply for an alias associated with a canonical name (CNAME) record, wherein the alias is for a primary domain; detect the CNAME record in the received DNS reply; and apply a load balancing algorithm for the primary domain, to a list of one or more network addresses provided in the DNS reply for the alias. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification