## CHECK_DNS_RESPONSETIME

Script: `check_dns_responsetime`

**check_dns_responsetime** check dns response time of all dns servers found in local /etc/resolv.conf

## Requirements

* `nslookup` query Internet name servers

## Standalone installation

From this repository you need next to this script:

* `inc_pluginfunctions` shared function for all IML checks written in bash

## Syntax

```txt
______________________________________________________________________

CHECK_DNS_RESPONSETIME 
v1.5

(c) Institute for Medical Education - University of Bern
Licence: GNU GPL 3
______________________________________________________________________

Loop over all defined dns servers (in /etc/resolv.conf) and check
each:
  - detect of port 53 is available (DNS service)
  - 5x check time of a nslookup for current host (www.example.com)

The a warning / critical response will be reached if the maximum time
of nslookup on the first dns server reaches a limit.

The critical response will be returned if the first of the 
nameservers is not available.

An unknown response will be returned if the current hostname 
(hostname -f) is no FQDN.

SYNTAX:
check_dns_responsetime [ -w VALUE -c VALUE -h ]

OPTIONS:

    -w VALUE       warning level  (default: 300)
    -c VALUE       critical level (default: 1000)
    -h or --help   Show this help.

```

### Parameters

(none)

## Examples

`$ check_disk-io -m io` returns

```txt
./check_dns_responsetime
OK: DNS check for www.example.com - found maximum was 46 ms - OK: all nameservers are reachable

---------- 1 - 8.8.4.4 
8.8.4.4 #1 >>> 36 ms
8.8.4.4 #2 >>> 28 ms
8.8.4.4 #3 >>> 24 ms
8.8.4.4 #4 >>> 30 ms
8.8.4.4 #5 >>> 31 ms
max: 36 ms
 ^
 :
 +--- 1st nameserver is relevant for total status of the check. Limits are warning=300 and critical=1000


---------- 2 - 8.8.8.8 
8.8.8.8 #1 >>> 39 ms
8.8.8.8 #2 >>> 35 ms
8.8.8.8 #3 >>> 33 ms
8.8.8.8 #4 >>> 46 ms
8.8.8.8 #5 >>> 43 ms
max: 46 ms

 |response-8-8-4-4=36;; response-8-8-8-8=46;;```