User's Manual

Appendix A IP Addresses and Subnetting
B222s User’s Guide
187
IP Address Conflicts
Each device on a net work m ust have a unique I P address. Devices wit h duplicate I P addresses on
the sam e net work will not be able t o access t he I nternet or other resources. The devices m ay also
be unreachable t hrough the network.
Conflicting Computer IP Addresses Example
More t han one device can not use t he sam e I P address. I n the following exam ple com put er A has a
st at ic ( or fixed) I P address that is t he sam e as t he I P address t hat a DHCP server assigns t o
com puter B which is a DHCP client. Neither can access t he I nternet . This problem can be solved by
assigning a different st atic I P address to com put er A or sett ing com puter A t o obt ain an I P addr ess
autom atically.
Figure 104 Conflicting Com put er I P Addresses Exam ple
Conflicting Router IP Addresses Example
Since a rout er connects different net works, it m ust have int erfaces using different net work
num bers. For exam ple, if a rout er is set bet ween a LAN and the I nt ernet ( WAN) , t he rout er ’s LAN
and WAN addresses m ust be on different subnet s. I n t he following exam ple, t he LAN and WAN are
on the sam e subnet . The LAN com puters cannot access the I nt ernet because the rout er cannot
rout e bet ween networ ks.
Figure 105 Conflicting Com put er I P Addresses Exam ple