Juniper Networks J-series Services Router J2320 - Manual (Page 156)

are added to the configuration to resolve hostnames in the order in which you list
them.
If you plan to include your router in several domains, you can add these domains to
the configuration so that they are included in a DNS search. When DNS searches are
requested, the domain suffixes are appended to the hostnames.
Default Gateway
A default gateway is a static route that is used to direct packets addressed to networks
not explicitly listed in the routing table. If a packet arrives at the Services Router with
an address that the router does not have routing information for, the router sends
the packet to the default gateway. The default gateway entry is always present in
the routing and forwarding tables.
Backup Router
You can specify a backup router to take over when the routing protocol process of
the Services Router is not running, usually when the Services Router is booting, or
if its routing protocol process has failed. Packets arriving at a Services Router in this
situation are routed to the backup router. When the routing protocol process starts
up again, the address of the backup router is removed from the routing and forwarding
tables of the Services Router. The backup router must be located on the same subnet.
NOTE: To configure a backup router, you must use the CLI or J-Web configuration
editor. You cannot configure a backup router with J-Web Quick Configuration.
Loopback Address
The loopback address is the IP address of the Services Router. The loopback address
ensures that the router provides an IP address to management applications. Because
it must always be available to hosts attempting to route packets to the router, the
loopback address resides on an interface that is always active, known as the loopback
interface (
lo0.0 ). Setting a loopback address ensures that the router can receive
packets addressed to the loopback address as long as the router is reachable though
any entry (ingress) interface. In addition, applications such as NTP, RADIUS, and
TACACS+ can use the loopback address as the source address for outgoing packets.
If you use the J-Web Set Up Quick Configuration page, you can either set a loopback
address of your choice or have the loopback address automatically set to
127.0.0.1
when you click Apply or OK to commit the configuration.
Built-In Ethernet Interface Address
The built-in Gigabit Ethernet interfaces, ge-0/0/0 through ge-0/0/3 , on the front
panel of the Services Router, are the interfaces through which you perform initial
router setup. The examples in this guide use the
ge-0/0/0 interface as the
management interface, but you can use any built-in Ethernet port for management.
134 ■ Basic Connectivity Overview
J2320, J2350, J4350, and J6350 Services Router Getting Started Guide