Hi,

• When i try this command

ping ukblx151.ukhx.astrazeneca.net -n 3 | grep icmp

it gives following error :
0821-077 ping: illegal packet size.

• But when i give command

ping ukblx151.ukhx.astrazeneca.net

It returns correct output.

Could you please help?

Can you check the man page of your ping command and see what the '-n' option stands for? What OS is this on?

By default (when packet-size is not specified), the size of transmitted packets is 64 bytes. The minimum value allowed for packet-size is 8 bytes, and the maximum value is 4095 bytes, on some systems is even 65000. If packet-size is smaller than 16 bytes, there is not enough room for timing information. In that case, the round-trip times are not displayed. In your case, the -n flag probably means something else, not the count number.]
The error number looks like AIX, I just tested AIX, and I seem to be right : -n flag means "packet-size", as well as "-s" whereas the count is "-c" flag.