100 meters or 328 feet unless a repeater (such as a switch or a router) is placed inline.
longest i have seen in a store was 100ft but if you need longer get a roll of Ethernet cable and 3 ends for it then make your own length of cable.
maximum is 100 meters or 328 ft
Repeaters are usually used in coaxial based ethernet networks. For this purpose they are used to extend the length of a network segment. For example, in a 10base2 ethernet network the maximum length of a segment is 180 meters. A repeater could join two segments together to increase the length of the network and the number of clients in the network. In today's modern networks you will see neither coaxial networks nor repeaters in a LAN. Repeaters are used for DSL transmissions, but not for LANS.
100BASE-T has a data trasnfer rate up to 100 Mbps. 100BASE-T is based on the older Ethernet standard. Its 10 times faster than Ethernet it is also called Fast Ethernet. The 100BASE-T standard is IEEE 802.3u
100 mbps
100Base-T network require usually cat5 maximum of cable length 100 meters to 380meters.
1000 base‑lx
The maximum length of a 10Base2 thinwire ethernet cable is 185 ft.
15 characters.
The overall network length exceeds IEEE 802.3 standards for that network type.A server on the network contains a faulty NIC.
Exceeding the maximum network length
Depends what you mean by a serial cable - Fibre, Ethernet, RS232, RS485, RS422, USB, HDMI, SMPTE292 are all examples of serial communications media. RS232 max length 50 ft Ethernet max length 100 m