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Cisco Bug: CSCup33404 - SPA 5xx handsets not using Additional records on the DNS SRV RESPONSE

Last Modified

Jan 27, 2017

Products (1)

  • Cisco Small Business SPA500 Series IP Phones

Known Affected Releases


Description (partial)

DNS servers of customer currently send the Additional A record in the DNS SRV response, which has the A record ?IP address ?of the proxy server. Through the SRV response has the A record, the phones tend to send the DNS A record request again.

Our DNS servers are smart to give the additional records on the DNS SRV which contains even the A RECORD .

The phones are not currently looking into the ADDITIONAL A record that is served on the SRV RESPONSE.

This is on all the phones across the SPA series that are exhibiting this behavior.

And going through the release notes for 7.5.5 I don't see any notes regarding DNS fix.

The traces that were captured were during a reboot . The phones were rebooted and the trace was captured for the entire DNS Cycle.

Phones are ignoring the TTL in the response and sending the DNS request again
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