DNS code to handle 500 internal error.

Resolves openbmc/openbmc-test-automation#1995

Signed-off-by: Prashanth Katti <prkatti1@in.ibm.com>
Change-Id: I14e9198c9bf202db21dabe8dc7b954b8260f48fa
diff --git a/redfish/managers/test_bmc_network_conf.robot b/redfish/managers/test_bmc_network_conf.robot
index 27d61c0..7c54192 100644
--- a/redfish/managers/test_bmc_network_conf.robot
+++ b/redfish/managers/test_bmc_network_conf.robot
@@ -684,8 +684,9 @@
     # static_name_servers  A list of static name server IPs to be
     #                      configured on the BMC.
 
+    # Currently BMC is sending 500 response code instead of 400 for invalid scenarios.
     Redfish.Patch  ${REDFISH_NW_ETH0_URI}  body={'StaticNameServers': ${static_name_servers}}
-    ...  valid_status_codes=[${valid_status_codes}]
+    ...  valid_status_codes=[${valid_status_codes}, ${HTTP_INTERNAL_SERVER_ERROR}]
 
     # Check if newly added DNS server is configured on BMC.
     ${cli_nameservers}=  CLI Get Nameservers