DNS Host Health Check
Note |
All RRs which have host-health-check attribute set to ping or gtp-echo are monitored periodically. Monitoring will start only after receiving first query for RR with host-health-check set to ping or gtp-echo. When host-health-check is set to ping, ICMP protocol will be used for monitoring. To work the feature effectively, the pinged systems should have default security settings that allow ping response. When host-health-check is set to gtp-echo, GTP-C v2 protocol (GTP-C Echo request and response) will be used for monitoring. |
DNS Host Health Check Configuration Settings
DNS Host Health Check comes with pre-configured settings, and is disabled by default on the DNS Server.
Attribute |
Description |
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host-health-check |
Enables or disables DNS Host Health Check in the DNS server. When Host Health Check is enabled, DNS server sends hhc- max-ttl as ttl in query reply for activeRRs. When DNSSecis enabled, dns server will add RR's which are not activeat the end of rr list in the query reply.When DNSSec is not enabled,dns server will not add RR's which are not activein rr list in the query reply. host-health-check is disabled on the DNS server by default, reload the DNS server after enabling host-health-check. |
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hhc-failed-domain-response |
Specifies how the DNS server responds to the requests when all RR's are down. The possible settings are: send-servfail - Configures the server to respond with SERVFAIL if all the RR's are down in nameset. send-all-rrs - Configures the server to respond with all rrs even all the RR's are down in nameset. drop-req - Configures the server to drop the query when all the RR's are down in nameset. |
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hhc-interval |
Specifies the time interval (in seconds) to check RR Sets for reachability. |
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hhc-max-ttl |
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hhc-max-init-ttl |
Specifies the maximum initial TTL (in seconds) to send in query reply when Host Health Check RR is queried for the first time.
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hhc-gtp-echo-port |
The port to which GTP-C echo messages are sent and received. |
Enabling Host Health Check
Local Advanced Web UI
Procedure
Step 1 |
On the Manage DNS Authoritative Server page, under the Host Health Check section, enable Host Health Check. |
Step 2 |
Click Save to save the changes and reload the DNS Authoritative Server. |
CLI Commands
Use the dns enable host-health-check to enable host health check and use dns reload to restart the DNS server.
Note |
Restart the DNS Server to apply the configuration changes successfully. |
Host Health Check RR Set Settings
Local Advanced Web UI
Note |
If DNSSEC is enabled on the zone, DNS server will add the RR's which are not active at the end of the rr list in the query reply. |
CLI Commands
zone name rrSet rr-name [set <host-health-check=off/ping/gtp-echo>] [get <host-health-check>] [unset <host-health-check>] [show]
The rrSet command sets/unsets the host-health-check flag on resource records for the rr-name. When this flag is set, the A and AAAA record's health will be monitored.
Note |
DNS server supports Global Unicast Address for IPv6 host health monitoring. |
DNS Host Health Check Statistics
You can view DNS Host Health Check Statistics through Web UI in the following ways:
Local Advanced Web UI
Click the Statistics tab on the Manage DNS Authoritative Server page to view the Host Health Check Statistics page. The statistics appear under the Host Health Check Statistics of both the Total Statistics and Sample Statistics categories.
Attribute |
Description |
hhc-domains |
Reports the total number of domains checked for ping and gtp-echo Host Health Check. |
hhc-domains-failed |
Reports the total number of domains check failed for ping and gtp-echo Host Health Check. When all the RRs in the RR set are down, this stat is incremented. |
hhc-domains-passed |
Reports the total number of domains check passed for ping and gtp-echo Host Health Check. When any RR in the RR set is up, this stat is incremented. |
hhc-rrs |
Reports the total number of RRs checked for ping and gtp-echo Host Health Check. |
hhc-rrs-passed |
Reports the total number of RRs that have passed ping and gtp-echo health check. |
hhc-rrs-failed |
Reports the total number of RRs that have failed ping and gtp-echo health check. |
hhc-ping-domains-failed |
Reports the total number of domains check failed for ping Host Health Check. When all the RRs in the RR set are down, this stat is incremented. |
hhc-ping-domains-passed |
Reports the total number of domains check passed for ping Host Health Check. When any RR in the RR set is up, this stat is incremented. |
hhc-ping-rrs |
Reports the total number of RRs checked for ping Host Health Check. |
hhc-ping-rrs-passed |
Reports the total number of RRs that have passed ping Host Health Check. |
hhc-ping-rrs-failed |
Reports the total number of RRs that have failed ping Host Health Check. |
hhc-gtp-echo-domains |
Reports the total number of domains checked for gtp-echo Host Health Check. |
hhc-gtp-echo-domains-failed |
Reports the total number of domains check failed for gtp-echo Host Health Check. When all the RRs in the RR set are down, this stat is incremented. |
hhc-gtp-echo-domains-passed |
Reports the total number of domains check passed for gtp-echo Host Health Check. When any RR in the RR set is up, this stat is incremented. |
hhc-gtp-echo-rrs |
Reports the total number of RRs checked for gtp-echo Host Health Check. |
hhc-gtp-echo-rrs-passed |
Reports the total number of RRs that have passed gtp-echo Host Health Check. |
hhc-gtp-echo-rrs-failed |
Reports the total number of RRs that have failed gtp-echo Host Health Check. |
CLI Commands
Use dns getStats dns-hhc total to view the host health check Total statistics and dns getStats dns-hhc sample to view the sampled counters statistics.
Note |
Restart the DNS Server to apply the configuration changes successfully. |