BGP "allowas-in" is usually used on the CE and "as-override" on the PE.

allowas-in - permit bgp updates containing local AS.

as-override - replace AS in BGP updates to local AS.

Type of DNS -
Primary, Secondary, Stub, Active Directory integrated and reverse look up

==================================================================================
IIS
Internet information services
==================================================================================

IAS
Internet Authentication Service
IAS is deployed in...

PING := Packet Internet Groper
CRC := Cyclic redundancy checksum


BGP is an Interdomain Routing Protocol (IDRP)