ltm monitor dns
ltm monitor dns(1) BIG-IP TMSH Manual ltm monitor dns(1)
NAME
dns - Configures a Domain Name System (DNS) monitor.
MODULE
ltm monitor
SYNTAX
Configure the dns component within the ltm monitor module using the
syntax in the following sections.
CREATE/MODIFY
create dns [name]
modify dns [name]
options:
accept-rcode [no-error | anything]
adaptive [enabled | disabled]
adaptive-divergence-type [relative | absolute]
adaptive-divergence-value [integer]
adaptive-limit [integer]
adaptive-sampling-timespan [integer]
answer-contains [query-type | any-type | anything]
app-service [[string] | none]
defaults-from [name]
description [string]
destination [ip address][port]
interval [integer]
manual-resume [enabled | disabled]
qname [string]
qtype [a | aaaa]
recv [none | [string] ]
reverse [enabled | disabled]
time-until-up [integer]
timeout [integer]
transparent [disabled | enabled]
up-interval [integer]
edit dns [ [ [name] | [glob] | [regex] ] ... ]
options:
all-properties
non-default-properties
DISPLAY
list dns
list dns [ [ [name] | [glob] | [regex] ] ... ]
show dns [ [ [name] | [glob] | [regex] ] ... ]
show running-config dns
show running-config dns [ [ [name] | [glob] | [regex] ] ... ]
options:
all-properties
non-default-properties
one-line
partition
DELETE
delete dns [name]
Note: You cannot delete default monitors.
DESCRIPTION
You can use the dns component to configure a custom monitor. This type
of monitor verifies the DNS service by attempting to send DNS requests
generated using the parameters provided to a pool, pool member, or
virtual server and validating the DNS response.
EXAMPLES
create dns my_dns defaults-from dns qname www.test.com
Creates a monitor named my_dns that inherits properties other than
qname from the default DNS monitor.
list dns
Displays the properties of all of the DNS monitors.
OPTIONS
accept_rcode
Specifies the RCODE required in the response for an 'up' status.
The default value is no-error.
The options are:
no-error
Specifies that the status of the node will be marked up if
the received dns message has RCODE = NOERROR.
anything
Specifies that the status of the node will be marked up
irrespective of the RCODE in the dns message received.
adaptive
Specifies whether the adaptive feature is enabled for this
monitor. Not all monitors support the adaptive feature.
adaptive-divergence-type
Specifies whether the adaptive-divergence-value is relative or
absolute.
adaptive-divergence-value
Specifies how far from mean latency each monitor probe is allowed
to be. If adaptive-divergence-type is relative, this value is a
percentage deviation from mean (e.g. 50 would indicate the probe
is allowed to exceed the mean latency by 50%.) If adaptive-
divergence-type is absolute, this value is an offset from mean in
milliseconds (e.g. 250 would indicate the probe is allowed allowed
to exceed the mean latency by 250 ms.) A probe that exceeds
latency is counted the same as a probe that is not received, so in
the typical scenario, it will require three missed latencies in a
row to mark a pool member or node down (i.e. a 15-second interval
with a 46-second timeout, would require three missed probes before
the pool member or node would be marked down.)
adaptive-limit
Specifies the hard limit, in milliseconds, which the probe is not
allowed to exceed, regardless of the divergence value. For
example, if this value is 500, then the probe latency may not
exceed 500 ms even if that would still fall within the divergence
value.
adaptive-sampling-timespan
Specifies the size of the sliding window, in seconds, which
records probe history. For example, if this value is 300, then a
sliding window of the last five minutes' probe history will be
used for calculating probe mean latency and standard deviation.
answer_contains
Specifies the record types required in the answer section of the
response in order to mark the status of a node up. The default
value is query-type.
The options are:
query-type
Specifies that the response should contain at least one
answer of which the resource record type matches the qtype.
any-type
Specifies that the dns message should contain at least one
answer.
anything
Specifies that an empty answer section is enough to mark the
status of the node up.
app-service
Specifies the name of the application service to which the monitor
belongs. The default value is none. Note: If the strict-updates
option is enabled on the application service that owns the object,
you cannot modify or delete the monitor. Only the application
service can modify or delete the monitor.
defaults-from
Specifies the name of the monitor from which you want your custom
monitor to inherit settings. The default value is dns.
description
User defined description.
destination
Specifies the IP address and service port of the resource that is
the destination of this monitor. Possible values are:
*:* Specifies to perform a health check on the IP address and
port supplied by a pool member.
*:port
Specifies to perform a health check on the server with the IP
address supplied by the pool member and the port you specify.
IP address:port
Specifies to mark a pool member up or down based on the
response of the server at the IP address and port you
specify.
IP address:port (with the transparent option enabled)
Specifies to perform a health check on the server at the IP
address and port you specify, route the check through the IP
address and port supplied by the pool member, and mark the
pool member (the gateway) up or down accordingly.
glob Displays the items that match the glob expression. See help glob
for a description of glob expression syntax.
interval
Specifies, in seconds, the frequency at which the system issues
the monitor check when either the resource is down or the status
of the resource is unknown. The default value is 5 seconds.
Important: F5 Networks recommends that when you configure this
option and the up-interval option, whichever value is greater be a
multiple of the lesser value to allow for an even distribution of
monitor checks among all monitors.
manual-resume
Specifies whether the system automatically changes the status of a
resource to up at the next successful monitor check. The default
value of the manual-resume option is disabled.
Note that if you set the manual-resume option to enabled, you must
manually mark the resource as up before the system can use it for
load balancing connections.
name Specifies a unique name for the component. This option is required
for the commands create, delete, and modify.
partition
Displays the administrative partition within which the component
resides.
qname
Specifies the query name that the monitor send a DNS query for.
The default value is Enter a query name.
qtype
Specifies the query type of that the monitor sends a query. The
default value is a.
The options are:
a Specifies that the monitor will send a DNS query of type A.
aaaa Specifies that the monitor will send a DNS query of type
AAAA.
recv Specifies the ip address that the monitor looks for in the dns
response's resource record sections. The ip address should be
specified in the dotted-decimal notation or ipv6 notation. The
default value is none. If no recv value is specified, then the dns
message will be checked against accept_rcode and answer_contains
monitor parameters respectively.
regex
Displays the items that match the regular expression. The regular
expression must be preceded by an at sign (@[regular expression])
to indicate that the identifier is a regular expression. See help
regex for a description of regular expression syntax.
reverse
Specifies whether the monitor operates in reverse mode. When the
monitor is in reverse mode, a successful receive string match
marks the monitored object down instead of up. You can use the
this mode only if you configure recv option.
The default value is disabled, which specifies that the monitor
does not operate in reverse mode. The enabled value specifies that
the monitor operates in reverse mode.
time-until-up
Specifies the amount of time, in seconds, after the first
successful response before a node is marked up. A value of 0
(zero) causes a node to be marked up immediately after a valid
response is received from the node. The default value is 0 (zero).
timeout
Specifies the number of seconds the target has in which to respond
to the monitor request. The default value is 16 seconds. If the
target responds within the set time period, it is considered up.
If the target does not respond within the set time period, it is
considered down. Also, if the target responds with a RESET packet,
the system immediately flags the target as down without waiting
for the timeout interval to expire.
transparent
Specifies whether the monitor operates in transparent mode.
Monitors in transparent mode can monitor pool members through
firewalls. The default value is disabled.
up-interval
Specifies, in seconds, the frequency at which the system issues
the monitor check when the resource is up. The default value is 0
(zero), which specifies that the system uses the value of the
interval option whether the resource is up or down.
Important: F5 Networks recommends that when you configure this
option and the interval option, whichever value is greater be a
multiple of the lesser value to allow for an even distribution of
monitor checks among all monitors.
SEE ALSO
create, delete, edit, glob, list, modify, regex, show, tmsh
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BIG-IP 2016-03-14 ltm monitor dns(1)