Lan Tcp/Ip - ZyXEL Communications VMG1312-B Series User Manual

• Som e I SPs choose t o dissem inat e t he DNS server addresses using t he DNS server ext ensions of
I PCP ( I P Cont rol Prot ocol) aft er t he connect ion is up. I f your I SP did not give you explicit DNS
servers, chances are t he DNS servers are conveyed t hrough I PCP negot iat ion. The Device
support s t he I PCP DNS server ext ensions t hrough t he DNS proxy feat ure.
Please not e t hat DNS proxy works only when t he I SP uses t he I PCP DNS server ext ensions. I t
does not m ean you can leave t he DNS servers out of t he DHCP set up under all circum st ances. I f
your I SP gives you explicit DNS servers, m ake sure t hat you ent er t heir I P addresses in t he
D H CP Se t up screen.

8.10.4 LAN TCP/IP

The Device has built- in DHCP server capabilit y t hat assigns I P addresses and DNS servers t o
syst em s t hat support DHCP client capabilit y.
IP Address and Subnet Mask
Sim ilar t o t he way houses on a st reet share a com m on st reet nam e, so t oo do com put ers on a LAN
share one com m on net work num ber.
Where you obt ain your net work num ber depends on your part icular sit uat ion. I f t he I SP or your
net work adm inist rat or assigns you a block of regist ered I P addresses, follow t heir inst ruct ions in
select ing t he I P addresses and t he subnet m ask.
I f t he I SP did not explicit ly give you an I P net work num ber, t hen m ost likely you have a single user
account and t he I SP will assign you a dynam ic I P address when t he connect ion is est ablished. I f t his
is t he case, it is recom m ended t hat you select a net work num ber from 192.168.0.0 t o
192.168.255.0 and you m ust enable t he Net work Address Translat ion ( NAT) feat ure of t he Device.
The I nt ernet Assigned Num ber Aut horit y ( I ANA) reserved t his block of addresses specifically for
privat e use; please do not use any ot her num ber unless you are t old ot herwise. Let 's say you select
192.168.1.0 as t he net work num ber; which covers 254 individual addresses, from 192.168.1.1 t o
192.168.1.254 ( zero and 255 are reserved) . I n ot her words, t he first t hree num bers specify t he
net work num ber while t he last num ber ident ifies an individual com put er on t hat net work.
Once you have decided on t he net work num ber, pick an I P address t hat is easy t o rem em ber, for
inst ance, 192.168.1.1, for your Device, but m ake sure t hat no ot her device on your net work is
using t hat I P address.
The subnet m ask specifies t he net work num ber port ion of an I P address. Your Device will com put e
t he subnet m ask aut om at ically based on t he I P address t hat you ent ered. You don't need t o change
t he subnet m ask com put ed by t he Device unless you are inst ruct ed t o do ot herwise.
Private IP Addresses
Every m achine on t he I nt ernet m ust have a unique address. I f your net works are isolat ed from t he
I nt ernet , for exam ple, only bet ween your t wo branch offices, you can assign any I P addresses t o
t he host s wit hout problem s. However, t he I nt ernet Assigned Num bers Aut horit y ( I ANA) has
reserved t he following t hree blocks of I P addresses specifically for privat e net works:
• 10.0.0.0
• 172.16.0.0
• 192.168.0.0 — 192.168.255.255
VMG1312-B Series User's Guide
— 10.255.255.255
— 172.31.255.255
Chapter 8 Home Networking
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