WO2002010912A1

WO2002010912A1 - Resolving hierarchical addresses using servers load balancer

Info

Publication number: WO2002010912A1
Application number: PCT/US2001/041472
Authority: WO
Inventors: David Edwin Blacka; Mark A. Kosters; William J. Sylvester
Original assignee: Verisign, Inc.
Priority date: 2000-08-01
Filing date: 2001-07-31
Publication date: 2002-02-07
Also published as: AU2001281367A1

Abstract

The present invention provides a system, method, and article of manufacture for resolving a hierarchical address into an IP address. The system includes a first set of plurality of name server processes for resolving the hierarchical address and a second set of plurality of name server processes for resolving the hierarchical address, wherein each of the name server processes in the second set of plurality of name server processes has a corresponding process in the first set of plurality of name server processes. The system also includes a load balancer for receiving a name resolution request that includes the hierarchical address and for sending the request to either one of the first set of plurality of name server processes or to the corresponding process in the second set of plurality of name server processes to resolve the hierarchical address into an IP address.

Description

RESOLVING HIERARCHICAL ADDRESSES USING SERVERS LOAD BALANCER

BACKGROUND OF THE INVENTION

A. Field of the Invention

The present invention relates to resolving a hierarchical address, for example, an address that includes a domain name, and more particularly, to a system and

method for resolving a hierarchical address quickly and efficiently using a plurality of

name server processes and a load balancer.

B. Description of the Related Art

In recent years, online networks, such as the Internet, have experienced

explosive growth and success due to their ability of providing a vast array of

resources, such as information, quickly and efficiently. For example, many

organizations have made some or all of their resources available to their customers via

web sites, which may be accessed using the Internet. h the online networks, the resources may be located on one or more

computers, each of which may have a unique IP (Internet Protocol) address.

Moreover, to access a computer in the online networks, one needs the IP address

associated with that computer. Remembering IP addresses, however, is difficult

because IP addresses are 32-bit numbers that are expressed as four 8-bit values

separated by periods, such as " 193.193.193.1. " To solve this difficulty, a hierarchical

naming scheme may be used. This naming scheme uses words and phrases to create easy to remember hierarchical addresses, which may then be translated into IP addresses by using a DNS (Domain Name System). For example, with the use of

DNS, one may need to only remember the hierarchical address

"server.dev.example.com" to go to the computer with the IP address of "193.193.193.100."

The hierarchical address may include a host name and a domain name. If the

hierarchical address includes a host name and a domain name, it is commonly referred

to as a fully qualified domain name. The host name, for example, may be the name of

the computer that includes the resources and the domain name may be a sequence of domains separated by periods. Domains include the root-level domain and

subdomains, such as top-level domains and second-level domains, as shown in FIG.

1. The root-level domain is at the top of the hierarchy. Generally, the root-level

domain uses a null label. If desired, it may, however, be expressed by a period. Every

domain name also has a top-level domain, such as "uk" for countries, "com" for commercial organizations, "edu" for educational institutes, "net" for network

organizations, and "mil" for military. Domain names may also include second-level

domains, such as "netsol.com," "example.com," "nsi.com," "duke.edu," and

"intemic.net." Although not shown in FIG. 1, other subdomains may include third-

level domains, such as "dev.example.com." For example, in the address "server.dev.example.com," the root level domain is present and is using a null label,

"com" is the top-level domain, "example.com" is the second-level domain, "dev.example.com" is the third-level domain, and "server" is the host name.

As mentioned in the foregoing description, DNS translates the hierarchical

address into the IP address. DNS is a distributed system and primarily uses UDP (User Datagram Protocol) and sometimes uses TCP (Transmission Control Protocol) as the underlying protocols. DNS includes clients and name servers. The name servers may be processes, such as BIND (Berkeley Internet Name Daemon) and Microsoft's DNS service. In DNS, a client may send a name resolution request or query to the name server asking the name server for translation of a hierarchical address into an IP address, hi response, the name server translates this request into the IP address. The process of translating is also known as resolving.

In recent years, domain names have become an important part of an organization. Moreover, in online networks, such as the Internet, an organization must register a domain name with a registrar, such as Network Solutions, Inc., before the organization can use the domain name. To register a domain name, the organization may need to provide various contact and technical information to the registrar. Technical information may include the IP address of at least two name servers in case one name server is not available. These name servers may be owned and operated by the organizations themselves or by third parties, such as an Internet Service Provider (ISP) or a registrar. The registrar will keep records of the contact information and submit the technical information to a central directory known as the registry. This registry provides other computers in the online network, such as the Internet, information about the organization's domain. This information may include name server information, so that others can access the organization's resources, such as a web site or send e-mail to the users within the organization.

Each name server in DNS may be responsible or have authority over one or more portions of the hierarchical address. This portion is known as a zone. The name server may store all address mappings for a zone and answer client name resolution requests for the names within the zone. For example, in "server.dev.example.com,"

"example.com" may be a zone and "dev.example.com" may be another zone, and

either same or different name servers may have authority over these two zones.

Moreover, to resolve "server.dev.example.com," one may first need to query the

"example.com" zone, which may in response provide the IP address for

"dev.example.com," and then, query "dev.example.com" zone, which may in turn

provide the IP address for "server.dev.example.com."

FIG. 2 shows an exemplary block diagram of a traditional DNS. As shown in

FIG. 2, a traditional DNS may include a client 100, a local name server 200, a root-level name server 300, a top-level name server 400, second-level domain servers

510 and 520, all of which are interconnected by a network 600. While the

components of FIG. 2 are shown as logical devices, one skilled in the art would

readily understand that each is associated with respective physical devices. For

example, the client 100 may be a physical device, such as a personal computer or a

laptop; network 600 may be the Internet; and each of the name servers may be a name

server process, such as BIND Version 8.1.2, that is running on a respective server

computer, such as a Sun Ultra 5 running the Sun Solaris operating system. Moreover,

although not shown in FIG. 2, it is known to one skilled in the art that other

components may exist in a traditional DNS. For example, normally, each name server has a corresponding name server for failover. Thus, in FIG. 2, although only a

corresponding second-level name server 520 is shown for the second-level name

server 510, the root-level name server 300 and top-level name server 400 also may have corresponding name servers for failover.

The local name server 200 may be responsible for resolving a hierarchical address included in a name resolution request into an IP address, and for sending the request to another name server if the local name server does not have the IP address associated with the hierarchical address. For example, an organization may have a local server for caching the IP address of any hierarchical address that it resolves so that the local server does not have to send this request to another name server every time a client requests resolution of a particular hierarchical address. Alternatively, the organization's Internet Service Provider (ISP) may host the local name server 200 to quickly resolve hierarchical addresses for its customers, such as an organization. The other name servers, such as the root-level name server 300, top-level name server 500, and second-level domain servers 510 and 520 may be responsible for particular zones and assist in resolving hierarchical addresses. For example, the root-level name server may contain information about the root-level domain.

The process of accessing resources using a traditional DNS will be described now by referring to FIG. 2. For example, assume that in FIG. 2, the top-level name server 400 has authority over the "com" zone and the second-level name servers 510 and 520 have authority over many zones, including "example.com." Furthermore, assume that a customer wants to access resources on an organization's web site, whose hierarchical address is "www.example.com." In order to access this web site, the user connects to the network 600, such as the Internet, and sends a name resolution request to the local server 200 by typing the address, "www.example.com" using a browser, such as NETSCAPE NAVIGATOR or INTERNET EXPLORER, on the client 100. To resolve this name resolution request, the local name server 200 may look in its local cache for any zones that correspond to the requested hierarchical address. If the current request is for an IP address that matches a previous request, the local server 200 may respond to the request immediately using the information stored in the local cache.

If the local server 200 does not find a zone corresponding to the requested

address, however, the local server 200 may relay the request to the root-level server

300. The root-level server 300 may have authority for the root-level domain and may reply with the IP address of a name server for a top-level domain, such as "com" and

"edu," to the local name server 200. In the present example, the root-level name

server may supply the IP address of the "com" top-level name server 400 because it

has authority over the "com" zone.

Next, the local name server 200 may send the name resolution request to the

top-level name server 400. The top-level name server may reply with the LP addresses

of both the second-level name servers 510 and 520 because they have authority over

"example.com." As described in the foregoing description, the root-level name server

300 and top-level name server 400 also may have corresponding name servers for failover. Therefore, in case the root-level name server 300 or the top-level name

server 400 is not available in the foregoing process, the name resolution requests may

be sent to the corresponding root-level name server or the top-level name server,

respectively.

Once the local name server 200 receives a reply with the LP addresses of the second-level name servers, the local name server 200 may send the name resolution request to the first name server listed in the reply and if that name server does not

respond, then, to the next name server listed in the reply. The reply may list the

addresses in the order determined by the top-level server. For example, some name

servers may return IP addresses in a random manner. In the present example, if the reply listed server 510 and then, server 520, the local name server 200 may send the name resolution request to the server 510. If the server 510 does not respond, the local name server 200 may send the request to the server 520. In the present example, the server 510 or 520 will look into the zone file for "example.com" and return the IP address for "www.example.com" to the local name server 200, which in turn sends the IP address to the client 100. The client 100 may use the IP address to visit the web site.

Subsequently, if the client 100 repeats the same name resolution request, the local server 200 may look in the local cache and may find the IP address. The local name server 200 then may transmit the address to the computer 100 without having to access any other name servers. The local name server 200 may cache all the information that it receives for an amount of time that is referred to as the TTL (Time to Live). The name server administrator for the zone that contains the data decides on the TTL for the data.

As described in the foregoing description, name servers make it easy for one to remember hierarchical addresses and are an important part of DNS. Thus, the name servers must be reliable as well as be able to quickly and efficiently resolve client name resolution requests. Currently available name servers, however, have many limitations, which may lead to unreliability as well as slow and inefficient name resolution.

One problem with the current name servers is that they provide limited failover and load balancing ability, which may result in a poor quality of service. For example, as described in the foregoing description, if one of the second-level name servers in FIG. 2 is not available, the local server 200 may send the name resolution request to the other one. Since DNS is normally queried over UDP, which is a connectionless protocol, the local name server 200 must wait for a few seconds before

the request may be sent to the other name server. Moreover, the organization hosting

the name servers to which the request is being sent has no control of automatically

switching to the second name server when the first one is not working or is not

available. In FIG. 2, if server 510 is not working or is not available, the organization

that operates servers 510 and 520 may not automatically redirect these requests to the

server 520. Thus, for failover, the order in which the local name server queries the

second-level name server is important, but as mentioned in the foregoing description,

this order may be determined by the top-level name servers. Similarly, for load

balancing, the organization that hosts the two second-level name servers may not have

any control over load balancing and the load balancing may depend on the order

determined by the top-level name servers.

Another problem with the current name servers is that they may have a zone limit of 65,536 zones. As a result, organizations, such as Network Solutions, Inc., which have authority over domains that have thousands of zones, such as second-level

domains, may have to add more name servers to serve the needs of their customers.

Adding more name servers, however, creates security problems because of the

problem of securing additional server computers. When additional name servers are

added, one may need to add an equivalent number of physical server computers for

running these name servers and securing these additional servers may be difficult. In

addition, adding more- physical server computers may require physical space, which may be expensive.

Still another problem with the current name servers is that these servers may not be highly available. For example, if the second-level name servers 510 and 520

each have 30,000 zones and if the administrator of the name servers makes a change to one or more of the 30,000 zones, the administrator may need to reload the zone, which may take a substantial amount of time and the server that is being reloaded may

not be available. As a result, usually, the administrator will reload the zone on the

two servers at different times so that at least one of the servers is available for name

resolution requests. For example, the administrator may reload server 510 first and

then, reload server 520. The local name server 200 may be trying to request a name

resolution from the server that is being reloaded and thus, may have to wait and then,

send a request to the other server.

Accordingly, there is presently a need for a system and method that resolves a

hierarchical address quickly and efficiently.

SUMMARY OF THE INVENTION

The present invention provides a system, a method, and an article of

manufacture for resolving a hierarchical address into an IP address. The system

includes a first set of plurality of name server processes for resolving the hierarchical

address and a second set of plurality of name server processes for resolving the

hierarchical address, wherein each of the name server processes in the second set of

plurality of name server processes has a corresponding process in the first set of

plurality of name server processes. The system also includes a load balancer for

receiving a name resolution request that includes the hierarchical address and for

sending the request to either one of the first set of plurality of name server processes or to the corresponding process in the second set of plurality of name server processes to resolve the hierarchical address into an IP address.

hi addition, the present invention provides a method for resolving a hierarchical address into an IP address. The method includes running a first set of

plurality of name server processes for resolving the hierarchical address and running a

second set of plurality of name server processes for resolving the hierarchical address,

wherein each of the name server processes in the second set of plurality of name

server processes has a corresponding process in the first set of plurality of name server

processes. The method also includes receiving, at a load balancer, a name resolution

request that includes the hierarchical address and sending the request to either one of

the first set of plurality of name server processes or to the corresponding process in the second set of plurality of name server processes to resolve the hierarchical address

into an IP address.

Moreover, the present invention provides a computer-readable medium

containing instructions for causing a computer to perform a method for resolving a

hierarchical address into an IP address. The method includes running a first set of plurality of name server processes for resolving the hierarchical address and running a

the first set of plurality of name server processes or to the corresponding process in the second set of plurality of name server processes to resolve the hierarchical address into an IP address. Furthermore, the present invention provides a system that includes a first

computer running a plurality of name server processes and a second computer running a plurality of name server processes. The system also includes a load balancer

interfacing the first computer and the second computer such that the load balancer

sends a request to either the first computer or the second computer to resolve a first

network address into a second network address.

The present invention also provides a method for resolving one or more

network addresses. The method includes running a plurality of name server processes

on a first computer and running a plurality of name server processes on a second

computer. The method also includes receiving a request that includes a first network

address and sending the request to either the first computer or the second computer to

resolve the first network address into a second network address such that respective

loads on the first computer and the second computer are maintained below respective predetermined levels.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated in and constitute a part of this

specification and, together with the description, explain the advantages and principles of the invention, hi the drawings,

FIG. 1 is an exemplary diagram illustrating the hierarchy of domains in a network;

FIG. 2 is an exemplary block diagram illustrating components of a traditional Domain Name System (DNS);

FIG. 3 is an exemplary system diagram illustrating an embodiment of the present invention;

FIG. 4 is an exemplary block diagram illustrating the components a client;

FIG. 5 is a portion of an exemplary data structure in a load balancer;

FIG. 6 is an exemplary flowchart illustrating the steps performed by a load

balancer for name resolution;

FIG. 7 is an exemplary system diagram illustrating another embodiment of the

present invention; and

FIG. 8 is an exemplary system diagram illustrating another embodiment of the

present invention.

DETAILED DESCRIPTION

The following detailed description of the invention refers to the accompanying

drawings. While the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described

without departing from the spirit and scope of the invention. The following detailed

description does not limit the invention. Instead, the scope of the invention is defined

by the appended claims and their equivalents.

The present invention provides a system and method to resolve a hierarchical

address, such as one that includes a domain name, quickly and efficiently by using a

plurality of name server processes and a load balancer. For example, with the use of

the present invention, an organization may run multiple name server processes on

server computers and may use a load balancer to balance the name resolution requests

for resolving hierarchical addresses between corresponding name server processes running on each of the server computers. The IP addresses associated with the plurality of name servers may be assigned to the load balancer, which may listen on a standard port, such as port 53, for any name resolution requests sent to the name

servers. Then, the load balancer may forward the name resolution requests for

resolution of the hierarchical addresses into IP addresses to the appropriate name

server processes, which may be listening on non-standard ports. The load balancer

may also provide quick and automatic failover ability between corresponding name

server processes on each of the server computers. Furthermore, the present invention

may provide the ability to have more than 65,536 zones on a single computer and may

reduce the number of physical machines that need to be secured.

The foregoing example is intended to be illustrative of the features of the

present invention as opposed to limiting it in any manner. Moreover, the system and

method of the present invention are not limited to any particular organization, user, or

resource. An organization may include, but is not limited to, an individual, a business, a government entity, and a non-profit organization. A user may include, but

is not limited to, an employee and a customer. A resource may include, but is not

limited to, data, applications, and documents.

The above-noted features, other aspects, and principles of the present

invention may be implemented in various system or network configurations to provide

automated and computational tools for quick and efficient name resolution. Such

configurations and applications may be specially constructed for performing the

various processes and operations of the invention or they may include a general purpose computer or computing platform selectively activated or reconfigured by program code to provide the necessary functionality. The processes disclosed herein

are not inherently related to any particular computer or other apparatus, and may be implemented by a suitable combination of hardware, software, and/or firmware. For

example, various general purpose machines may be used with programs written in

accordance with teachings of the invention, or it maybe more convenient to construct

a specialized apparatus or system to perform the required methods and techniques.

The present invention also relates to computer readable media that include

program instruction or program code for performing various computer-implemented

operations based on the methods and processes of the invention. The media and

program instructions may be those specially designed and constructed for the purposes

of the invention, or they may be of the kind well-known and available to those having

skill in the computer software arts. The media may take many forms including, but

not limited to, non- volatile media, volatile media, and transmission media. Non¬

volatile media includes, for example, optical or magnetic disks. Volatile media includes, for example, dynamic memory. Transmission media includes, for example, coaxial cables, copper wire, and fiber optics. Transmission media can also take the

form of acoustic or light waves, such as those generated during radio-wave and infra¬

red data communications. Examples of program instructions include both machine

code, such as produced by compiler, and files containing a high level code that can be

executed by the computer using an interpreter.

FIG. 3 is an exemplary system diagram illustrating an embodiment of the

present invention, i this embodiment, the system includes a client 100, a load

balancer 700, and server computers 810 and 820, all of which are interconnected by

network 600. Network 600 may be a single or a combination of any type of computer network, such as the Internet, an Intranet, an Extranet, a Local Area Network (LAN),

or a Wide Area Network (WAN), for example. These as well as other network configurations are known to those skilled in the art and are also within the scope of the present invention.

The server computers 810 and 820 may run a plurality of name server

processes and the load balancer 700 may balance the requests for resolving

hierarchical addresses between corresponding name server processes on each of the

server computers. These server computers may be used to run name server processes

for local, root-level, top-level, second-level, and even other subdomains, such as third-

level domains. Moreover, although not shown, other name servers, such as local

name servers, root-level name servers, top-level name servers, and second-level name

servers may be connected to the network 600. Furthermore, two server computers are

illustrated for exemplary purposes only, but more or less than two server computers

maybe used for load balancing and failover depending on the requirements of a

particular organization.

Each of the components shown in FIG. 3 will be described in detail now.

Client 100 of FIG. 3 may include, but is not limited to, a personal computer, a

handheld computer, or any similar device known to those skilled in the art. As shown

in FIG. 4, the client 100 may include a browser 110, such as a world wide web

browser like NETSCAPE NAVIGATOR and/or INTERNET EXPLORER; other

software and data storage 120; at least one input device 130, such as a keyboard or a

mouse; at least one communications device 140, such as a modem or a network

interface card (NIC); at least one processor 160; memory 150; and at least one output device 170, such as a monitor, all of which may communicate with each other, for

example via a communication bus 180. The memory 150 maybe random access memory (RAM), read only memory, or both. Other clients and their components are known to those skilled in the art and are also within the scope of the present invention.

The server computers 810 and 820 maybe any computer, for example, that

manages resources. These server computers 810 and 820 may include storage

devices, such as a tape drive or hard drive, for storing, for example, program

instructions or program code. For example, the sever computers 810 and 820 may be

Sun E4500 computers running the Sun Solaris operating system. Each of the server

computers may run a plurality of name server processes. For example, each of the

server computers may run multiple instances of BIND version 8.1.2, which is a name

server process.

To run multiple processes, a unique port or an IP address may be needed.

With the server computers 810 and 820, a unique port may be used for each instance of the name server process. For example, if BIND version 8.1.2 is being used, the "namedxonf ' file maybe modified to reflect the unique port for each process on each

server computer. Specifically, the directive "listen-on port XXXX {YYYY;};" may

be used in the "named. conf ' file to assign a unique port number to each of the name

server processes, h this option, "XXXX" would define the port number, and

"YYYY" would define the IP address. If "any" was used for the IP address, the name

server process would be responsible for handling requests regardless of which IP

address the requests were directed to. Furthermore, the port number may be a

standard or non-standard port. For example, name servers normally listen on the

standard port 53, but in the present invention, the name servers may be configured to listen on non-standard ports, such as port 6001.

Moreover, each name server process on the server computer 810 may have a

corresponding name server process on the server computer 820 for failover and load balancing. The name server processes corresponding to each other are referred to as a

name server pair. For example, if server 810 has name server processes A and B, and server 820 has name server processes C and D, A may correspond to C and may be

classified as a name server pair, and C may correspond to D and may be classified as

another name server pair. The processes in each of the pairs may have identical zone

data and may be used for failover and load balancing.

The load balancer 700 may provide load balancing and failover capability. For

example, the load balancer 700 may be F5 Networks, hic.'s BIG-IP product, or a

similar computing device with a storage medium, such as a tape drive or a hard drive.

The load balancer 700 may be configured to listen to a plurality of IP addresses. Moreover, since a name server process normally listens on the standard port 53 of a

computer, the load balancer 700 may be configured to listen on port 53 for any name server requests. Furthermore, the total number of IP addresses may be equivalent to

the total number of name server processes running on the server computers 810 and 820. Moreover, upon receiving a name resolution request for resolving a hierarchical

address, the load balancer 700 may send the request to the appropriate name server

process on the server computer 810 and/or 820.

For example, if BIG-IP is being used as the load balancer 700, BIG-IP may be

configured to listen on port 53 for any name resolution requests that are directed to the

IP addresses of the above-mentioned name servers, A, B, C, and D, and then, be configured to forward the requests to the appropriate process. Specifically, the

"bigip.conf ' file maybe modified to configure BIG-IP.

FIG. 5 shows a portion of an exemplary "bigip.conf file. As shown in FIG. 5, assuming the IP address of A is "193.193.193.1," B is "193.193.193.2," C is "193.193.193.3," D is "193.193.193.4," server 810 is "207.32.193.10," and server 820

is "207.32.193.20," and the port numbers for A, B, C, and D are 6001, 6002, 6001,

and 6002, respectively, BIG-IP may be configured to first listen to the IP addresses

corresponding to A, B, C, and D, and then, forward the request to the appropriate

process running on server computers 810 or 820 using the IP address of the server

computer and the port number associated with the name server process, hi FIG. 5, the

lines that start with'Vip" direct BIG-IP to listen for any requests, which are directed to

the IP addresses that follows "vip," on port 53. Then, the lines that start with "define"

direct BIG-IP to forward the received requests to the port numbers on the respective

IP addresses that follow "define." The load balancer 700 considers the name server processes on each of the name server pairs to be equivalent and thus, may balance

requests between each of the corresponding processes.

FIG. 6 and an example will be used to explain the operation of the load

balancer 700 in more detail, hi this example, assume that the "example.com" zone is

located on the name servers A and C, and that "nsi.com" zone is located in B and D,

and a user wants to access "www.example.com" and "www.nsi.com." To access

"www.example.com," the user may ask a local name server, such as the local name

server 200, for the resolution of this address to IP addresses. If the local name server

does not have the information for this address in the cache, the local name server may

send a query to a top-level domain server and then, a second-level domain server, as

explained with the description of FIG. 2. Eventually, the local name server will obtain

the IP addresses corresponding to A and C. As described in the foregoing description, the order of the IP addresses for A and C will depend entirely on the top-level name

server. For example, the top-level name server may be setup to return the IP addresses in a random order.

Depending on the order of the IP addresses, the local name server may send a

request to A or C for resolution ofwww.example.com." If the address of A is listed

first, the local name server will send the request to 193.193.193.1 on port 53. The

load balancer 700, such as BIG-IP, receives the request, as shown in a step 610 in

FIG. 6. Then, the load balancer 700 determines which of name server processes

should receive the request, for example, by referring to the "bigip.conf file, as shown in a step 620. Then, depending on the load and availability of the servers 810 and

820, the load balancer 700 will send the request to the appropriate process on these

servers, as shown in a step 630. hi the present example, using the "bigip.conf file

shown in FIG. 5, the load balancer 700 may send the request to port 6001 on 207.32.193.10 (or server 810) or port 6001 on 207.32.193.20 (or server 820)

depending on the load of each of the servers.

h one embodiment, the load balancer 700 may load balance between the

processes running on these two different servers in a round robin manner. For

example, the load balancer 700 may send the first received request to port 6001 on

207.32.193.10 and then, send the next received request to port 6001 on 207.32.193.20,

and continue in this round robin manner for any succeeding requests. In other

embodiments, other load balancing techniques also may be used depending on the

abilities of the load balancer. For example, the load balancer may provide an

improved quality of service by maintaining the loads on a particular process or a server computer below a predetermined level.

hi response to the name server request received from the load balancer 700, the name server process looks in its zone file and provides the load balancer 700 with the IP address associated with the address in the name resolution request. Finally, in a

step 640, the load balancer sends the IP address received from the name server process to the local server.

On the other hand, if the address of C is listed first in the response from the

top-level domain server, the local name server will send the request to 193.193.193.3

on port 53. Then, the load balancer 700 may again forward this request to port 6001

on 207.32.193.10 (or server 810) or port 6001 on 207.32.193.20 (or server 820)

depending on the load of each of the servers.

Similarly, if name resolution for "www.nsi.com" was requested instead of

"www.example.com," the load balancer 700 would balance between the corresponding name server processes, B and D.

In addition to load balancing, the present invention provides many advantages

over the traditional methods of name resolution. One advantage is that if the load

balancer 700 determines that either a name server process or the server computer running the name server process is not available, the load balancer 700 automatically

sends the request to the other corresponding process running on the second server

computer. For example, if in step 630, the load balancer 700 determines that the

process listening on port 6001 on 207.32.193.10 is not working, it may automatically send the request to port 6001 on 207.32.193.20 without having to wait for a

substantial amount of time. In addition, the requesting local name server may not

need to send a request to a different name server because the load balancer 700 automatically redirects the request.

Another advantage of the present invention is that the name server processes

are available even when the zones are being loaded. For example, if a zone is being reloaded on a particular server computer, the load balancer automatically sends the

request to the corresponding name server process on the other server computer. A

related advantage is that the administrator only needs to modify one set of zone files

because the name server processes use the same set of zone files.

Still another advantage of the present invention is that an organization may run

multiple name server processes on one server computer, thus overcoming the zone limit of 65,536 and reducing the number of machines that need to be secured.

Another advantage may be the added security provided by a load balancer 700. For

example, the load balancer 700 may be setup to only receive name server requests and

disregard any other requests.

The present invention is not limited to any particular name server process or

load balancer, histead, the present invention may be used with any name server

process that can listen on a non-standard port. For example, the name server

processes may include DENTS or TINYDNS. addition, the load balancer is not limited to BIG-IP, it may be, for example, a load balance made by Cisco Systems,

ie, Radware, Inc., HydraWeb Technologies, Inc., Resonate, Inc., or Foundry Networks, hie.

Moreover, it will be apparent to those skilled in the art that various

modifications and variations can be made in the system and method of the present

invention and in construction of this invention without departing from the scope or

spirit of the invention. For example, as shown in FIG. 7, in an alternative

embodiment, the present invention maybe modified to include two load balancers,

700 and 710, in case one load balancer becomes unavailable. FIG. 8 illustrates another exemplary embodiment of the present invention. This embodiment is similar to the one shown in FIG. 3 with the exception of the server computers 810, and 820. In this embodiment, the system includes only one server computer, 810, which may run a plurality of name server processes. Moreover, each of the name server processes may have a corresponding name server process, and the load balancer 700 may balance the name resolution requests between the corresponding name server processes running on the server computer 810 depending on the availability of the name server processes. For example, the server 810 may run four name server processes E, F, G, and H. E may correspond to G and may be classified as a name server pair, and F may correspond to H and may be classified as another name server pair. As a result, the load balancer 700 may balance the name resolution requests between the processes E and G, and F and H.

As mentioned in the forgoing description, the difference between the embodiment shown in FIG. 8 and FIG. 3 is that FIG. 3 includes an additional server 820, which may be used for redundancy purposes. Furthermore, in other embodiments, additional server computers may be added depending on the needs of a particular organization.

Although the present invention was described for use with name servers, the present invention may be used with a wide range of applications. For example, the present invention may be used to load balance traffic directed to web servers. Specifically, the IP addressees for a plurality of web servers maybe assigned to the load balancer, which may listen on the standard port 80, for any requests directed to the plurality of web servers. Upon receiving a request, the load balancer may forward the request to the appropriate web server, which may be listening on a non-standard port and may be running on a server computer. The load balancer may, for example,

balance the load between corresponding web servers running on one or more server

computers.

Moreover, other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention

disclosed herein. It is intended that the specification and examples be considered as

exemplary only, with a true scope and spirit of the invention being indicated by the

following claims.

Claims

WHAT IS CLAIMED IS:

1. A system for resolving a hierarchical address into an IP address, comprising:

a first set of plurality of name server processes for resolving the hierarchical

address;

a second set of plurality of name server processes for resolving the hierarchical

address, wherein each of the name server processes in the second set of plurality of

name server processes has a corresponding process in the first set of plurality of name

server processes; and

a load balancer for receiving a name resolution request that includes the

hierarchical address and for sending the request to either one of the first set of plurality of name server processes or to the corresponding process in the second set of

plurality of name server processes to resolve the hierarchical address into an IP

address.

2. The system according to claim 1, wherein each of the first set of

plurality of name server processes and the second set of plurality. of name server

processes listens on a different port.

3. The system according to claim 2, wherein the load balancer has a

plurality of IP addresses corresponding to the total number of name server processes.

4. The system according to claim 3, wherein if one of the first set of plurality of name server processes is unavailable, the load balancer seiids the request to the corresponding name server process in the second set of plurality of name server processes.

5. The system according to claim 1, wherein the load balancer listens for name resolution requests on port 53.

6. The system according to claim 1, wherein the load balancer balances

name resolution requests between the corresponding processes in the first set of

plurality of name server processes and the second set of plurality of name server

processes.

7. The system according to claim 6, wherein the load balancer balances

the name resolution requests between the corresponding processes in the first set of plurality of name server processes and the second set of plurality of name server

processes in a round robin manner.

8. The system according to claim 1, wherein each of the first set of plurality of name server processes and the second set of name server processes is a

BIND process.

9. The system according to claim 1, wherein the load balancer includes a

BIG-IP.

10. The system according to claim 1, wherein the first set of plurality of name server processes and the second set of plurality of name server processes run on a computer.

11. The system according to claim 1 , wherein the first set of plurality of

name server processes and the second set of plurality of name server processes run on

different computers.

12. A method for resolving a hierarchical address into an IP address,

comprising the steps of:

running a first set of plurality of name server processes for resolving the

hierarchical address;

running a second set of plurality of name server processes for resolving the hierarchical address, wherein each of the name server processes in the second set of

plurality of name server processes has a corresponding process in the first set of plurality of name server processes;

receiving, at a load balancer, a name resolution request that includes the hierarchical address; and

sending the request to either one of the first set of plurality of name server

processes or to the corresponding process in the second set of plurality of name server

processes to resolve the hierarchical address into an IP address.

13. The method according to claim 12, further comprising the step of

configuring each of first set of plurality of processes and the second set of plurality of

processes to listen on a different port.

14. The method according to claim 13, further comprising the step of

assigning to the load balancer a plurality of IP addresses corresponding to the total

number of name server processes.

15. The method according to claim 14, wherein the step of sending the

request to either one of the first set of plurality of name server processes or one of the

second set of plurality of name server processes includes the step of sending the

request to one of the first set of plurality of name server processes, and if one of the

first set of processes is unavailable, then sending the request to the corresponding

name server process in the second set of plurality of name server processes.

16. The method according to claim 12, wherein the step of receiving the

name resolution request by the load balancer includes listening on port 53 for the

request.

17. The method according to claim 12, further comprising the step of

balancing, at the load balancer, name resolution requests between the corresponding

processes in the first set of plurality of name server processes and the second set of

plurality of name server processes.

18. The method according to claim 17, wherein the step of balancing the

name resolution requests by the load balancer is performed in a round robin manner.

19. The method according to claim 12, wherein each of the first set of plurality of name server processes and the second set of plurality of name server

processes is a BIND process.

20. The method according to claim 12, wherein the load balancer includes

a BIG-IP.

21. The method according to claim 12, wherein the step of running the first

set of plurality of name server processes and the step of running the second set of

plurality of name server processes are performed on a computer.

22. The method according to claim 12, wherein the step of running the first

plurality of name server processes are performed on different computers.

23. A computer-readable medium containing instructions for causing a

computer to perform a method for resolving a hierarchical address into an IP address,

comprising the steps of: running a first set of plurality of name server processes for resolving the

hierarchical address;

running a second set of plurality of name server processes for resolving the

sending the request to either one of the first set of plurality of name server processes or to the corresponding process in second set of plurality of name server

processes to resolve the hierarchical address into an IP address.

24. A system, comprising:

a first computer running a plurality of name server processes;

a second computer running a plurality of name server processes; and

a load balancer interfacing the first computer and the second computer such

that the load balancer sends a request to either the first computer or the second

computer to resolve a first network address into a second network address.

25. A method for resolving one or more network addresses, comprising the

steps of: running a plurality of name server processes on a first computer;

running a plurality of name server processes on a second computer;

receiving a request that includes a first network address;

sending the request to either the first computer or the second computer to