350-801 · Question #440
An administrator troubleshoots a DNS issue with Cisco UCM and observes that the hostname resolution returns the wrong IP address. The DNS team informs the administrator that the A/AAA record was…
The correct answer is B. Flush the current cache using this CLI command: admin:utils network name-service hosts cache. When DNS records are updated but Cisco UCM still resolves to stale IP addresses, the CUCM's internal DNS cache needs to be cleared. The admin:utils network name-service hosts cache CLI command is used to flush this cache.
Question
An administrator troubleshoots a DNS issue with Cisco UCM and observes that the hostname resolution returns the wrong IP address. The DNS team informs the administrator that the A/AAA record was recently updated on the DNS server. Which action must be taken on Cisco UCM to reflect the correct entries?
Options
- ARestart the DNS server to flush any stale entries
- BFlush the current cache using this CLI command: admin:utils network name-service hosts cache
- CDelete the arp entry of the host utils network arp delete
- DFlush the current cache using this CLI command: admin:utils network name-service hosts cache
How the community answered
(49 responses)- A2% (1)
- B86% (42)
- C8% (4)
- D4% (2)
Why each option
When DNS records are updated but Cisco UCM still resolves to stale IP addresses, the CUCM's internal DNS cache needs to be cleared. The `admin:utils network name-service hosts cache` CLI command is used to flush this cache.
Restarting the DNS server is outside the scope of UCM administration and would affect all clients using that DNS server; the issue is with UCM's local cache.
The `admin:utils network name-service hosts cache` command on the Cisco UCM CLI is specifically designed to flush the server's DNS hostname resolution cache, forcing it to query the DNS server for fresh records and resolve any stale entries.
Deleting the ARP entry using `utils network arp delete` would clear the MAC-to-IP mapping, which is unrelated to hostname-to-IP resolution issues.
This option is identical to B, making B the correct answer as it is the appropriate CLI command to flush the DNS cache on Cisco UCM.
Concept tested: Cisco UCM DNS cache management
Source: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/cli_reference/8_0_2/cli_reference_802/cli_network.html
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