Hi Rajakumari,
SAP return code 497 means:
C_NIHOSTTOADDR 497 NiHostToAddr failed
Or in words: in that group there must be a hostname, which the DNS server of your network (or the /etc/hosts file) cannot resolve to an IP address.
So either it's a configuration problem (like hostname misspelled...). --> Let the SAP admin, who defined that server group check this.
Or it's a network problem. --> Let the network admin check this.
Best Regards, Ulrich