Create / Edit Service Test - DNS Page

Use this page to define a DNS service test. This test can help you determine whether the DNS service is responding to queries in a timely manner.

The Agent will determine the status of a DNS service by performing a single DNS request lookup and by validating that the response is correct. The time between sending the request and receiving the response is an indicator of the service's performance.

Test Parameters

Field	Description
Address	This is the address to lookup. Based on the type of query, you can enter either the IP Address, Email Record or the Alias.
Type of Query	Indicates the type of DNS query being defined by the service test. This can be: IP Address (A): Enter a host name in the "Address" field, and the IP address(es) for that host will be retrieved by the beacon. Email Record (MX): Enter an email domain name (e.g. "oracle.com") in the "Address" field, and the IP addresses of the relevant SMTP servers will be retrieved by the beacon. Alias (CNAME): The user should enter a host alias in the "Address" field, and the canonical host name will be retrieved by the beacon. For example, "www.yahoo.com" might resolve to "www.yahoo.akadns.net".
Expected Results	The expected result of the DNS query. This is can be a set of IP addresses or aliases separated by commas.
DNS Server IP / Port	The IP address or Port number of the DNS server. If no values are specified, then the agent will determine the DNS server based on the host's configuration.
Client IP / Port	If multiple interfaces are available, you can specify which interface is to be used.
Protocol	Specify the protocol to be used for the DNS query. This can be UDP or TCP.
Timeout	This is the amount of time that the agent will wait for the test to complete. If the timeout expires, then the status of the test will be considered down.
Number of Retries	This is the number of times that a script will be run (if it returns non-zero) until the status is determined to be down.
Interval Between Retries	This is the interval between consecutive retries.

Metrics Collected

Status

Indicates whether the query was successful.

User Action
Consult the Results metric for details.

Metric	Description
Total Response Time	Total time required to receive a response from the DNS service. User Action Unusually slow response times can occur if the DNS server has to perform a lookup before it can respond. If the total response time is consistently slow, then either the network may be slow, or the DNS server may be having trouble generating a response. Try using traceroute to diagnose network issues.
Total Connect Time	Time taken to connect to the DNS service. This metric is only collected for queries that have TCP selected for the protocol property. User Action A slow Total Connect Time suggests that network congestion is a problem.
TTL	A response to a DNS request may contain multiple answers. Each answer in a DNS response has a TTL (Time To Live) that indicates the number of seconds that the answer may be cached by a client. The TTL value reported here is the maximum TTL of all the answers in the DNS response. User Action If TTL values are low, then you may consider configuring your DNS service to allow caching for longer periods of time
Number of Retries	The total number of retries before a DNS lookup is successful. User Action If the Number of Retries is high, then packets were probably dropped on the network.
Number of Results	A response to a DNS request may contain multiple answers. This indicates the number of answers (e.g. the number of IP addresses) in the response from the DNS service. User Action If the number of results is not what it should be, then you will need to examine your DNS service's configuration.
Results	The results of the DNS query. In the event of a failure, the reason for the failure will be displayed here.

Related Topics

About Services

About Beacons

Types of Service Tests

Creating a Service

Enterprise Manager Information Roadmap