I85PREP
⌘ K
Telecom Professional Qualification study materials
Telecom Professional Qualification study resources

Telecom Professional Qualification: IP Networking, Routing, and Internet Protocols

Telecom Professional Qualification · Work through your exam, one topic at a time.

All guide sections

IP Networking, Routing, and Internet Protocols

This domain tests IPv4/IPv6 addressing and subnetting, interior and exterior routing behaviour, and the transport and support protocols that glue networks together. Subnetting is the highest-yield calculation; BGP path selection is the highest-yield recall item.

Addressing and subnetting

  • IPv4 is 32 bits. A /n block holds 2^(32−n) addresses; for normal host subnets two are reserved (network and broadcast), so usable hosts = 2^(32−n) − 2. Point-to-point links may use /31 (RFC 3021) and /32 is a host route.
  • Private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. Carrier-grade NAT uses 100.64.0.0/10. NAT/PAT translates many private hosts to few public addresses and breaks end-to-end transparency.
  • IPv6 is 128 bits, conventionally /64 per LAN, has no broadcast, and uses Neighbour Discovery instead of ARP; SLAAC and DHCPv6 provide addressing.

Routing

  • RIP is distance-vector with a 15-hop maximum; OSPF is link-state, split into areas, and computes cost as reference bandwidth ÷ interface bandwidth; IS-IS is the carrier alternative.
  • BGP is path-vector between autonomous systems. Best-path order: highest weight → highest LOCAL_PREF → locally originated → shortest AS_PATH → lowest origin type → lowest MED → eBGP over iBGP → lowest router ID.
  • Supporting technologies: MPLS with LDP or RSVP-TE, 802.1Q VLAN tags (12-bit ID, 4,094 usable), STP to break Layer 2 loops.

Transport and support protocols

TCP gives ordered, retransmitted delivery with windowing; UDP is connectionless and used by DNS (53), DHCP (67/68), RTP and SNMP (161). TLS protects 443, SIP uses 5060/5061, IPsec uses ESP (50) and IKE (500).

Worked example

Split 192.168.10.0/24 into /26 subnets. New mask 255.255.255.192; block size 64. Subnets: .0–.63, .64–.127, .128–.191, .192–.255. Each has 64 addresses, 62 usable. For the first subnet: network 192.168.10.0, usable 192.168.10.1–192.168.10.62, broadcast 192.168.10.63. The fourth subnet's broadcast is 192.168.10.255, not .254.

Traps that cost marks

  • Forgetting the two reserved addresses, so answering 64 hosts for a /26.
  • Mixing up which address is network and which is broadcast in the last subnet.
  • Reciting BGP attributes in the wrong order - weight and LOCAL_PREF are checked before AS_PATH length.
  • Assuming IPv6 requires NAT, or that it keeps ARP.
  • Using OSPF cost as hop count; it is bandwidth-derived and ties are broken by router ID.