The 192.168.0.0 network is not being propagated throughout the network. Observe the BGP
configuration commands from the advertising router. What is the reason the 192.168.0.0 route is
not being advertised?
router bgp 65111
neighbor 172.16.1.1 remote-as 65111
neighbor 172.16.2.1 remote-as 65112
network 192.168.0.0
network 10.0.0.0
!
ip route 192.168.0.0 255.255.0.0 null0

A.
The network 192.168.0.0 statement is missing mask 255.255.0.0

B.
The network 192.168.0.0 statement is missing mask 0.0.255.255.

C.
The network 10.0.0.0 statement is missing mask 255.0.0.0.

D.
The network 10.0.0.0 statement is missing mask 0.255.255.255.

E.
The auto-summary configuration is missing.

Explanation:
The “network” statement in other routing protocols (EIGRP, OSPF, RIP…) is used to enable
routing protocol on the interfaces within that “network” statement. But in BGP, the function of a
network statement is to tell the router to search the IP routing table for a particular network, and if
that network is found, originate it into the BGP database. But notice that you must have an exact
match in the IP routing table to appear the network in the BGP routing table (in this case we don’t
see the auto-summary command so we suppose it is disabled in this case). For example:+
network 10.10.10.0/8 will appear in BGP if network 10.10.10.0/8 appears in the IP routing table.+
network 10.10.10.0/24 will appear in BGP if network 10.10.10.0/24 appears in the IP routing table.
Therefore, in this question the static route “ip route 192.168.0.0 255.255.0.0 null0 was used to put
a route to 192.168.0.0/16 into the routing table (although it points to Null0 but this command really
makes that route appears in the routing table). But the “network 192.168.0.0 statement tells the
router to lookup network 192.168.0.0/24 (if the network statement under BGP-mode does not
specify a subnet mask, the default subnet mask of that class will be used). The router only finds
network 192.168.0.0/16 -> The network 192.168.0.0 is not being propagated throughout the
network because of the mismatch of the subnet mask.
Just for your information, in fact we have to suppose there is no entry of the network
192.168.0.0/24 exist in the routing table except the static route “ip route 192.168.0.0 255.255.0.0
null0. If such an entry exists (for example, a directly connected entry like “C 192.168.0.0/24 is
directly connected”) then the router still advertises it with the “network 192.168.0.0 (without mask

255.255.0.0) command.