Building and Modifying DNS Rules

Transcription

1 CHAPTER 7 Building and Modifying DNS Rules This chapter describes how to build and modify Domain Name System (DNS) rules on your GSS network. After you configure your source address lists, domain lists, answers, and answer groups, you are ready to begin constructing the DNS rules that will control global server load balancing on your GSS network. When building DNS rules, you specify the actions for the GSS to perform when it receives a request from a known source (a member of a source address list) for a known hosted domain (a member of a domain list). The DNS rule specifies which response (answer) is given to the requesting user s local DNS host (D-proxy) and how that answer is chosen. The GSS uses one of a variety of balance methods to determine the best response to the request, which is based on the status and load of your GSS host devices. Note Before you create DNS rules, see the GSS Architecture section in Chapter 1, Introducing the Global Site Selector. This chapter contains the following major sections: DNS Rule Configuration Overview Building DNS Rules Using the Wizard Building DNS Rules Using the DNS Rule Builder Modifying DNS Rules Suspending a Clause Reactivating a Clause Reactivating Operationally Suspended Clauses Suspending a DNS Rule Reactivating a DNS Rule Suspending or Reactivating All DNS Rules Belonging to an Owner Deleting a DNS Rule Configuring DNS Rule Filters Removing DNS Rule Filters Delegating to GSS Devices Where To Go Next OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide 7-1

2 DNS Rule Configuration Overview Chapter 7 Building and Modifying DNS Rules DNS Rule Configuration Overview DNS Rule Wizard Figure 7-1) guides you through the process of creating a DNS rule. The DNS Rule Wizard allows you to create source address lists, domain lists, answer groups, and balance methods as required. Owners, regions, and locations are not created as part of the DNS Rule Wizard, however. Instead, you must create them before using the wizard. The DNS sticky and network proximity global server load-balancing applications are configurable only from the DNS Rule Builder, not from the DNS Rule Wizard. Use the DNS Rule Builder to enable DNS sticky, proximity, or the manual reactivation function (see Managing Global Manual Reactivation of Answers and Clauses section on page 2-11) in a DNS rule. Figure 7-1 DNS Rule Wizard Introduction Page When you use the wizard, click the Next Back 1. DNS Rules 2. Rule Wizard 7-2

3 DNS Rule Builder You can use the DNS Rule Builder (see Figure 7-2) to quickly assemble DNS rules from source address lists, domain lists, owners, and answers that you have already created. By using the available fields and drop-down menus, you can assign a name for your rule and then configure the rule with up to three balance clauses for the GSS to choose an answer. The balance clauses that you configure in a DNS rule are evaluated in order. Parameters are established to determine when a clause is skipped and the next clause is used. A balance clause is skipped when any one of the following conditions exits: The least-loaded balance method is selected and the load threshold for all online answers is exceeded. The VIP answers in the specified VIP answer group are offline. Proximity is enabled for a VIP-type answer group and the Director Response Protocol (DRP) agents do not return any RTT values that meet the value set for acceptable-rtt Figure 7-2 DNS Rule Builder Window 7-3

4 Building DNS Rules Using the Wizard In addition, the DNS Rule Builder allows you to configure multiple clauses for your DNS rule; that is, you can configure additional answer group and balance method pairs that can be tried if the first answer group and balance method specified does not yield an answer. To access the DNS Rule Builder, perform the following steps: 1. Click the tab. 2. Click the Open Rule Builder Building DNS Rules Using the Wizard Note Note 1. Figure 7-3). 7-4

5 Figure 7-3 DNS Rules List Page page provides an overview of the steps necessary to create a DNS rule. Figure 7-4). This Figure 7-4 DNS Rule Wizard Introduction Page

6 Identifying a Source Address List in the DNS Rule Wizard Specifying a Domain List in the DNS Rule Wizard Configuring an Answer Group in the DNS Rule Wizard Choosing a Balance Method in the DNS Rule Wizard Reviewing the Summary Page in the DNS Rule Wizard Identifying a Source Address List in the DNS Rule Wizard Figure 7-5) allows you to identify a source address list, which is a list of address blocks that identify DNS proxies. Figure 7-5 DNS Rule Wizard Source Address List Page 1 Next Any Address Manually-entered source address list Next 7-6

7 Next Predefined source address list Figure 7-6) of the wizard to create your Source Address List. Configuring the source address list by using the wizard makes it available for use by other DNS rules. Figure 7-6 DNS Rule Wizard Source Address List Page 2 a. Enter a name for your Source Address List in the List Name field. b. List Owner c. d /32; /24; /16 3.

8 Specifying a Domain List in the DNS Rule Wizard Figure 7-8) allows you to specify the domains that users will request. Each GSS can support up to 2000 total domains. If using a KAL-AP type answer, the GSS can support up to 1024 domains managed by any single server load-balancing device such as a Cisco Content Services Switch (CSS) or Content Switching Module (CSM). 7-8

9 Figure 7-8 DNS Rule Wizard Domain List Page 1 Manually-entered domain list Next Predefined domain list Next Figure 7-9) of the wizard to manually configure the requested domains names. Configuring the domain list using the DNS Rule Wizard makes it available for use by other DNS rules. 7-9

10 Figure 7-9 DNS Rule Wizard Domain List Page 2 Hosted domains cannot exceed 128 characters. The following examples show domain names configured on the GSS: cisco.com support.cisco.com; cdn.cisco.com The GSS supports domain names that use wildcards. The GSS supports POSIX extended regular expressions when matching wildcards. Any request for a hosted domain that matches the pattern is directed accordingly. For example, assume that you have 20 or more possible domains, such as www1.cisco.com, www2.cisco.com, and so on. You can create a wildcard expression that covers all of those domains:.*\.cisco\.com 7-10

11 Chapter 7 Building and Modifying DNS Rules Building DNS Rules Using the Wizard 4. Figure 7-10 DNS Rule Wizard Domain List Page 3 a. b. Configuring an Answer Group in the DNS Rule Wizard OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

12 Building DNS Rules Using the Wizard Chapter 7 Building and Modifying DNS Rules DNS Rule Wizard Answer Group Page 1 Enter addresses Next group Next Select an existing answer Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide OL

13 Group Owner VIP Virtual IP (VIP) addresses associated with an SLB as such the Cisco CSS, Cisco CSM, Cisco IOS-compliant SLB, LocalDirector, web server, cache, or other geographically dispersed SLBs in a global network deployment. Name Server Configured DNS name server on your network that can answer queries that the GSS cannot resolve. CRA Content routing agents that use a resolution process called DNS race to send identical and simultaneous requests back to a user s D-proxy. Click Next to use the Answer Group Page 3 of the wizard to configure answers for your answer group. Proceed to Step 4. Use Answer Group Page 3 of the DNS Rule Wizard (see Figure 7-13) to configure answers for the specified answer group type: VIP, NS, or CRA.

14 5. a. b. c. Weight

15 Location Weight Location Next 6.

16 Building DNS Rules Using the Wizard Chapter 7 Building and Modifying DNS Rules a. b. Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide OL

17 Chapter 7 Building and Modifying DNS Rules Building DNS Rules Using the Wizard Choosing a Balance Method in the DNS Rule Wizard ) Note DNS Rule Wizard Balance Method Page OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

18 Reviewing the Summary Page in the DNS Rule Wizard

19 Chapter 7 Building and Modifying DNS Rules Building DNS Rules Using the Wizard DNS Rule Wizard Summary Page Query Type drop-down list: All The DNS rule is applied to all DNS queries that originate from a host on the configured source address list. For any request other than an A-record query (for example, MX or CNAME record), the GSS forwards the request to a name server configured in one of the three balance clauses. When the GSS receives the response from the name server, it then delivers the response to the requesting client D-proxy. When you choose All as the Match DNS Query Type, you must configure one balance clause to include a name server-type answer group. A record The DNS rule is applied only to answer address record (A- record) requests originating from a host on the configured source address list. For any request with an unsupported query types (for example, MX, PTR, or CNAME record) that match this DNS rule, those query types will be dropped and not answered by the GSS. For an AAAA query with a configured host domain, the GSS returns a NODATA (No Answer, No Error) response in order for the requester to make a subsequent A-record query. Choose an operating status for the rule from the Rule Status drop-down list: Active The DNS rule immediately begins processing requests. Suspended The DNS rule is listed on the DNS Rules list page but has a status of suspended. The DNS rule is not used to process any incoming DNS queries. Click Finish OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

20 DNS Rules DNS Rules Open Rule Builder

21 Create New DNS Rule Window 7.

22 Building DNS Rules Using the DNS Rule Builder Chapter 7 Building and Modifying DNS Rules Choose the answer group component of your first answer group/balance method pairing from the drop-down list. This is the first effort the GSS uses to select an answer for the DNS query. Choose the balance method for the answer group from the drop-down list. Your choice of balance methods changes based on the type of answer group (VIP, name server, or CRA) that you selected. Note 11. Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide OL

23 Chapter 7 Building and Modifying DNS Rules Building DNS Rules Using the DNS Rule Builder Create New DNS Rule Window With VIP-Type Answer Group Fields OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

24 Active Suspended Figure 7-20 Create New DNS Rule Window With CRA-Type Answer Group Fields

25 Active Suspended Save

26 Modifying DNS Rules Note Modify DNS Rule Using Rule Builder Interface Save DNS Rules Modify DNS Rule Using Wizard Finish Suspending a Clause Reactivating a Clause

27 Chapter 7 Building and Modifying DNS Rules Reactivating Operationally Suspended Clauses 4. Reactivating Operationally Suspended Clauses Suspending a DNS Rule OK 1. DNS Rules 2. Modify DNS Rule Using Wizard 3. Summary 4. Suspended 5. Finish OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

28 Reactivating a DNS Rule Chapter 7 Building and Modifying DNS Rules Reactivating a DNS Rule 1. DNS Rules 2. Modify DNS Rule Using Rule Builder Interface 3. Activate 4. OK 1. DNS Rules 2. Modify DNS Rule Using Wizard 3. Summary 4. Active 5. Finish Suspending or Reactivating All DNS Rules Belonging to an Owner Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide OL

29 Chapter 7 Building and Modifying DNS Rules Suspending or Reactivating All DNS Rules Belonging to an Owner Owners List Page 3. Figure 7-22 Modifying Owners Details Page OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

30 Owner Rules for This Owner OK Suspend All DNS Rules for This Activate All DNS Caution Site Selector Administration Guide Global Configuring DNS Rule Filters 1. 2.

31 Chapter 7 Building and Modifying DNS Rules Configuring DNS Rule Filters 3. Table 7-1 DNS Rules Filter Parameters Parameter Description Selection Examples Source Address List Filter Parameters IP Address Block Owner Domain List Filter Parameters IP address or address block assigned to a source address list associated with the DNS rule Name of the owner assigned to the source address list associated with the DNS rule VIP* NameServerList * Any System Education OL Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide

32 DNS Rules Filter Parameters (continued) Balance Clause Filter Parameters Answer Group Owner Answer Group Type Contains Answer Balance Method DNS Rule Filter Parameters Name of the owner assigned to the answer group associated with the DNS rule Type of answer group associated with the DNS rule Answer belonging to an answer group associated with the DNS rule Type of balance method (such as boomerang and ordered list) associated with the DNS rule VIP_answer_Group_1 VIP_answer_Group_2 VIP_* Any System HR CRA Name Server VIP * Boomerang Hashed Least-Loaded Order List Round-Robin Weighted Round-Robin

33 Removing DNS Rule Filters 4. No DNS rules match the filter specification. Removing DNS Rule Filters Delegating to GSS Devices Note

34 Where To Go Next Chapter 7 Building and Modifying DNS Rules Example 7-1 Sample BIND Zone Configuration File Delegating GSSs IN SOA ns1.cisco.com. postmaster.cisco.com. ( ; serial number 36000; refresh 10 hours 3600 ; retry 1 hour ; expire 42 days ; minimum 100 hours ) ; Corporate Name Servers for cisco.com IN NS ns1.cisco.com. IN NS ns2.cisco.com. ns1 IN A ns2 IN A ; Sub-domains delegated to GSS Network www IN NS gss1.cisco.com. IN NS gss2.cisco.com. media IN CNAME www ftp IN NS gss1.cisco.com. IN NS gss2.cisco.com. ; Glue A records with GSS interface addresses ; Cisco GSS Dallas gss1 IN A ; Cisco GSS London gss2 IN A Where To Go Next Cisco Global Site Selector GUI-Based Global Server Load-Balancing Configuration Guide OL