Dns Server Address; Pppoe; Ppp Mtu - ZyXEL Communications G-4100 V2 User Manual

4.5 DNS Server Address

DNS (Domain Name System) is for mapping a domain name to its corresponding IP address
and vice versa. The DNS server is extremely important because without it, you must know the
IP address of a machine before you can access it. The DNS server addresses that you enter in
the DHCP setup are passed to the client machines along with the assigned IP address and
subnet mask.
There are two ways that an ISP disseminates the DNS server addresses. The first is for an ISP
to tell a customer the DNS server addresses, usually in the form of an information sheet, when
s/he signs up. The second is to obtain the DNS server information automatically when a
computer is set as a DHCP client.

4.6 PPPoE

Point-to-Point Protocol over Ethernet (PPPoE) functions as a dial-up connection. PPPoE is an
IETF (Internet Engineering Task Force) standard specifying how a host personal computer
interacts with a broadband modem (for example DSL, cable, wireless, etc.) to achieve access
to high-speed data networks.
For the service provider, PPPoE offers an access and authentication method that works with
existing access control systems (for instance, RADIUS).
One of the benefits of PPPoE is the ability to let end users access one of multiple network
services, a function known as dynamic service selection. This enables the service provider to
easily create and offer new IP services for specific users.
Operationally, PPPoE saves significant effort for both the subscriber and the ISP/carrier, as it
requires no specific configuration of the broadband modem at the subscriber's site.
By implementing PPPoE directly on the ZyXEL Device (rather than individual computers),
the computers on the LAN do not need PPPoE software installed, since the ZyXEL Device
does that part of the task. Furthermore, with NAT, all of the LAN's computers will have
Internet access.

4.6.1 PPP MTU

A maximum transmission unit (MTU) is the largest size packet or frame, specified in octets
(eight-bit bytes) that can be sent in a packet- or frame-based network. The Transmission
Control Protocol (TCP) uses the MTU to determine the maximum size of each packet in any
transmission. Too large an MTU size may mean retransmissions if the packet encounters a
router that can't handle that large a packet. Too small an MTU size means relatively more
header overhead and more acknowledgements that have to be sent and handled.
Chapter 4 WAN, LAN and Server Setup
G-4100 v2 User's Guide
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