Source: slide screenshot (2026-07-23 07:03:44)

Concept

Typing ping with no arguments in privileged EXEC mode launches the extended ping dialog. IOS prompts for each option one at a time; pressing <enter> accepts the value shown in brackets [ ].

The key reason to use extended ping instead of plain ping 192.168.100.1 is the source address or interface option — it lets the router send the echo from a specific interface, which tests return routing from that subnet.

Full session (verbatim)

Boise# ping
Protocol [ip]:  <enter>
Target IP address:  192.168.100.1
Repeat count [5]:  <enter>
Datagram size [100]:  <enter>
Timeout in seconds [2]:  <enter>
Extended commands [n]:  y
Source address or interface:  10.0.10.1
Type of service [0]:  <enter>
Set DF bit in IP header? [no]: <enter>
Validate reply data? [no]:  <enter>
Data pattern [0xABCD]:  <enter>
Loose, Strict, Record, Timestamp, Verbose[none]:  <enter>
Sweep range of sizes [n]:  <enter>
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.100.1, timeout is 2 seconds:
Packet sent with a source address of 10.0.10.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 7/8/10 ms

Prompts explained

Prompt	Default	Value used	What it controls
Protocol	`ip`	default	Protocol stack to ping with
Target IP address	none	`192.168.100.1`	Destination being tested
Repeat count	`5`	default	How many echo requests to send
Datagram size	`100`	default	Packet size in bytes
Timeout in seconds	`2`	default	How long to wait for each reply
Extended commands	`n`	`y`	Must be `y` to reach the source-address prompt
Source address or interface	none	`10.0.10.1`	Source IP/interface the echo is sent from
Type of service	`0`	default	ToS / QoS marking
Set DF bit in IP header?	`no`	default	Don't Fragment bit — used for MTU/path-MTU testing
Validate reply data?	`no`	default	Compare returned payload against what was sent
Data pattern	`0xABCD`	default	Payload bit pattern (useful for line-quality tests)
Loose, Strict, Record, Timestamp, Verbose	`none`	default	IP header options; `Record` captures hops taken
Sweep range of sizes	`n`	default	Send a range of packet sizes to find MTU issues

Reading the output

Type escape sequence to abort. — press Ctrl+Shift+6 to stop the ping early.
Sending 5, 100-byte ICMP Echos to 192.168.100.1, timeout is 2 seconds: — echoes the chosen repeat count, datagram size, target, and timeout.
Packet sent with a source address of 10.0.10.1 — confirms the extended source option took effect.
!!!!! — five successful replies.
Success rate is 100 percent (5/5), round-trip min/avg/max = 7/8/10 ms — 5 of 5 replies returned; fastest 7 ms, average 8 ms, slowest 10 ms.

Ping response characters

Char	Meaning
`!`	Reply received (success)
`.`	Timed out waiting for a reply
`U`	Destination unreachable received
`Q`	Source quench (destination too busy)
`M`	Could not fragment
`?`	Unknown packet type
`&`	Packet lifetime exceeded (TTL)

Why the source address matters

A normal ping uses the exit interface's IP as the source. If the far end has no route back to that interface's subnet, the ping fails even though the path forward is fine. Setting the source to 10.0.10.1 tests reachability from that subnet, which is how you verify the return path a real host would use.

Practical uses of the extended options

Set DF bit + Sweep range of sizes → find the largest packet that crosses the path without fragmentation (path MTU discovery / MTU mismatch troubleshooting).
Repeat count raised high → soak-test a link for intermittent drops.
Data pattern → detect line-encoding or bit errors on serial/WAN circuits.
Record option → capture the hops traversed inside the IP header.
Timeout increased → avoid false failures on slow satellite or high-latency WAN links.