in wikipedia we have a good definition for in degree and out degree in a graph: " The degree of a node is the number of connections or edges the node has to other nodes. in-degree is the number of incoming edges and out-degree is the number of outgoing edges". so what is the definition of out-degree and in-degree in computer networks? is the number of unique ip addresses that a host send packets to that? or is the number of tcp connections that a host establish to other hosts (number of SYN packets that the host sends to other hosts) plus the number of udp packets that the host send to other hosts? or is the number of flows that originate from one host (flow= same destination ip address, same source ip address, same destination port and same source port)? or ....
See the linked WP article:
If a network is directed, meaning that edges point in one direction from one node to another node, then nodes have two different degrees, the in-degree, which is the number of incoming edges, and the out-degree, which is the number of outgoing edges.
That refers to network (or graph) theory - a network can be of directed nature, ie. links only work in one direction (network theory also applies to things like power distribution or road traffic).
Practical computer networks work in both directions simultaneously, links are bidirectional. Hence, there's no in-degree vs out-degree.