Talk:Ping: Difference between revisions
Jump to navigation
Jump to search
Created page with "== Why am I seeing DUP! when using ping on a linux machine with WiFi adapter? == * https://unix.stackexchange.com/questions/13254/what-could-dup-mean-when-using-ping It mean..." |
No edit summary |
||
| Line 4: | Line 4: | ||
It means the reply packet is a duplicate. ICMP responses contain a sequence number. Sometimes you'll actually get more than one reply with the same sequence number. This is usually caused by faulty networks. Wireless networks often rely on re-sending packets if they don't get proper verification, and if the first one actually worked, the re-send will be a duplicate. In normal usage duplicates are discarded. In ping replies they are noted because they tell you something about how the network is functioning. For example, if you are getting 100% duplicates some fault detection mechanism is likely broken. | It means the reply packet is a duplicate. ICMP responses contain a sequence number. Sometimes you'll actually get more than one reply with the same sequence number. This is usually caused by faulty networks. Wireless networks often rely on re-sending packets if they don't get proper verification, and if the first one actually worked, the re-send will be a duplicate. In normal usage duplicates are discarded. In ping replies they are noted because they tell you something about how the network is functioning. For example, if you are getting 100% duplicates some fault detection mechanism is likely broken. | ||
64 bytes from 10.0.0.254: icmp_seq=5 ttl=64 time=1.90 ms | |||
64 bytes from 10.0.0.254: icmp_seq=5 ttl=64 time=2.84 ms (DUP!) | |||
Revision as of 19:56, 12 July 2024
Why am I seeing DUP! when using ping on a linux machine with WiFi adapter?
It means the reply packet is a duplicate. ICMP responses contain a sequence number. Sometimes you'll actually get more than one reply with the same sequence number. This is usually caused by faulty networks. Wireless networks often rely on re-sending packets if they don't get proper verification, and if the first one actually worked, the re-send will be a duplicate. In normal usage duplicates are discarded. In ping replies they are noted because they tell you something about how the network is functioning. For example, if you are getting 100% duplicates some fault detection mechanism is likely broken.
64 bytes from 10.0.0.254: icmp_seq=5 ttl=64 time=1.90 ms 64 bytes from 10.0.0.254: icmp_seq=5 ttl=64 time=2.84 ms (DUP!)