مفهوم کد های ! علامت تعجب و ... نقطه و U در پینگ کردن داخل سوییچ و روتر های سیسکو به شرح زیر است :
| ! | Each exclamation point indicates receipt of a reply. |
| . | Each period indicates the network server timed out as it waits for a reply. |
| U | A destination unreachable error PDU was received. |
| Q | Source quench (destination too busy). |
| M | Could not fragment. |
| ? | Unknown packet type. |
| & | Packet lifetime exceeded. |