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Key Facts: BUT Réseaux et Télécommunications Exam

180 ECTS

Total university credits awarded over 3 years, conferring the national grade de licence

Arrêté du 15 avril 2022

Level 6

National qualification level under France Compétences

France Compétences

22–26 weeks

Mandatory workplace internship or alternance period across the 3-year curriculum

Programme National BUT R&T

80% core

Proportion of common core competencies shared across all five specialized parcours

Arrêté du 15 avril 2022 Annexe 22

10/20

Minimum average required to validate each competency teaching unit (UE)

Règlement d'évaluation BUT

The BUT Réseaux et Télécommunications (R&T) is France's 3-year national university degree (180 ECTS, Level 6) for telecommunications, computer networks, and cloud infrastructure. Delivered by IUTs and evaluated via continuous assessment (CCI) and SAÉ projects, it covers advanced IP routing, optical and radio transmissions, cloud automation, cybersecurity defense, and operator networks. This 100-question English bank is an analytical study adaptation of the official curriculum.

Sample BUT Réseaux et Télécommunications Practice Questions

Try these sample questions to review concepts for the BUT Réseaux et Télécommunications exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1An enterprise network engineer needs to allocate subnets for four branch offices requiring 120, 60, 28, and 12 host addresses respectively from the parent block 172.16.10.0/23. Using Variable Length Subnet Masking (VLSM) to minimize unused address space, what is the valid subnet allocation and the remaining unallocated block?

A.172.16.10.0/25 (120 hosts), 172.16.10.128/26 (60 hosts), 172.16.10.192/27 (28 hosts), 172.16.10.224/28 (12 hosts); remaining block is 172.16.10.240/28 and 172.16.11.0/24

B.172.16.10.0/24 (120 hosts), 172.16.11.0/25 (60 hosts), 172.16.11.128/26 (28 hosts), 172.16.11.192/27 (12 hosts); remaining block is 172.16.11.224/27

C.172.16.10.0/25 (120 hosts), 172.16.10.64/26 (60 hosts), 172.16.10.128/27 (28 hosts), 172.16.10.192/28 (12 hosts); remaining block is 172.16.11.0/24

D.172.16.10.0/26 (120 hosts), 172.16.10.64/26 (60 hosts), 172.16.10.128/27 (28 hosts), 172.16.10.160/28 (12 hosts); remaining block is 172.16.10.192/26 and 172.16.11.0/24

Explanation: 120 hosts requires a /25 (128 addresses, 126 usable: 172.16.10.0 - 172.16.10.127). 60 hosts requires a /26 (64 addresses, 62 usable: 172.16.10.128 - 172.16.10.191). 28 hosts requires a /27 (32 addresses, 30 usable: 172.16.10.192 - 172.16.10.223). 12 hosts requires a /28 (16 addresses, 14 usable: 172.16.10.224 - 172.16.10.239). The remaining unallocated space in the /23 block (which spans 172.16.10.0 to 172.16.11.255) is 172.16.10.240/28 and the entire 172.16.11.0/24.

2A network architect is designing an IPv6 addressing plan for a regional campus. The ISP has assigned the global routing prefix 2001:db8:acad::/48. Following standard IPv6 subnetting best practices, how many /64 subnets can the campus create, and why is /64 the standard subnet prefix length?

A.65,536 subnets; /64 is required for Stateless Address Autoconfiguration (SLAAC) using EUI-64 or RFC 7217 stable privacy interface identifiers

B.256 subnets; /64 is required because router hardware TCAM tables can only index 64-bit boundaries

C.4,096 subnets; /64 is required to accommodate 48-bit MAC addresses with 16-bit padding

D.16,777,216 subnets; /64 is required because DHCPv6 cannot assign addresses across prefix boundaries longer than /64

Explanation: From a /48 prefix to a /64 subnet mask, there are 64 - 48 = 16 bits dedicated to the subnet field (bits 49 through 64), yielding 2^16 = 65,536 individual /64 subnets. The /64 prefix length is mandated by RFC 4291 and RFC 4862 for Stateless Address Autoconfiguration (SLAAC), which constructs a 64-bit interface identifier (IID) from an EUI-64 MAC address or via randomized stable privacy algorithms (RFC 7217).

3In a multi-area OSPFv2 deployment, what is the specific role of a Type 3 Summary LSA, and which router generates it?

A.It advertises inter-area network prefixes originated within one area into another area; it is generated by an Area Border Router (ABR)

B.It advertises external routes redistributed from outside the OSPF autonomous system; it is generated by an Autonomous System Boundary Router (ASBR)

C.It lists all routers attached to a broadcast multi-access network segment; it is generated by the Designated Router (DR)

D.It advertises the route to reach an ASBR across non-backbone areas; it is generated by an Area Border Router (ABR)

Explanation: Type 3 Summary LSAs (Summary-LSA: IP network) describe inter-area network routes. They are generated and flooded by Area Border Routers (ABRs) into adjacent areas (such as Area 0 or from Area 0 into non-backbone areas) to enable inter-area routing without flooding intra-area topology details (Type 1 and Type 2 LSAs).

4An autonomous system running OSPFv2 contains a remote branch configured as a 'Totally Stubby Area' (TSA). How do internal routers within this area receive routing information about external destinations and networks in other OSPF areas?

A.The ABR blocks Type 3, 4, and 5 LSAs and injects a single Type 3 Summary LSA with destination 0.0.0.0/0

B.The ABR blocks only Type 5 LSAs and propagates all Type 3 and Type 4 LSAs unchanged

C.The ABR converts Type 5 external LSAs into Type 7 LSAs and floods them throughout the area

D.Internal routers must establish an eBGP peering session with the ABR to learn default and external routes

Explanation: A Totally Stubby Area (a Cisco enhancement widely implemented across vendors) filters not only external routes (Type 4 and Type 5 LSAs) but also inter-area summary routes (Type 3 LSAs). The ABR injects a single default route (0.0.0.0/0) encoded as a Type 3 Summary LSA, drastically reducing internal routing table size and SPF calculation overhead.

5Two enterprise routers are connected over an Ethernet segment and configured with OSPF priority 100 and 50 respectively. Both routers are restarted simultaneously. What determines which router becomes the Designated Router (DR)?

A.The router with the higher OSPF priority (priority 100) becomes the DR

B.The router with the highest Router ID (RID) becomes the DR regardless of priority

C.The router with the lowest IP address on the broadcast interface becomes the DR

D.The router that completes the 2-Way handshake first always becomes the DR regardless of priority or RID

Explanation: During an OSPF DR/BDR election on a broadcast multi-access network, routers compare priority values first. The router with the highest non-zero priority wins the DR election. If priorities are identical (a tie), the router with the highest Router ID (RID) is elected. Since priority 100 > priority 50, the router with priority 100 is elected DR.

6In Border Gateway Protocol (BGP), what is the fundamental purpose of the AS-Path attribute in eBGP sessions?

A.To enforce loop prevention by discarding update packets containing the local Autonomous System number, and to serve as a path-length metric

B.To compute Dijkstra's shortest path algorithm across inter-domain links based on link bandwidth

C.To negotiate cryptographic authentication parameters between external BGP peers

D.To signal quality-of-service class markings between disparate telecommunication operators

Explanation: BGP is a path-vector protocol. When an eBGP speaker receives an UPDATE, it inspects the AS_PATH attribute. If its own local Autonomous System Number (ASN) appears in the AS_PATH list, the router discards the prefix to prevent routing loops. Additionally, in the BGP best-path selection algorithm, a shorter AS_PATH is preferred over a longer one (all prior attributes like Weight and Local Preference being equal).

7A dual-homed enterprise has two Internet connections via ISP-A (AS 65001) and ISP-B (AS 65002). The enterprise engineer wants outbound traffic to prefer ISP-A for all internal clients while keeping ISP-B as an active backup. Which BGP attribute should be configured on the enterprise border routers, and where does it propagate?

A.Local Preference (LOCAL_PREF); set higher on prefixes received from ISP-A, propagating only within the local Autonomous System across iBGP

B.Weight; set higher on ISP-A, propagating across all iBGP and eBGP peers

C.Multi-Exit Discriminator (MED); set lower on ISP-A, propagating to all upstream transit providers

D.Origin code; set to Incomplete (?), propagating across the global Internet

Explanation: Local Preference is a well-known discretionary BGP attribute that dictates outbound traffic exit points for an Autonomous System. Higher LOCAL_PREF is preferred (default 100). It is exchanged exclusively between iBGP peers within the same AS and is never advertised to eBGP peers.

8Why does internal BGP (iBGP) require either a full mesh of peering sessions between all internal routers or the implementation of Route Reflectors / BGP Confederations?

A.Because iBGP rules forbid advertising a route learned from one iBGP peer to another iBGP peer to prevent internal routing loops

B.Because TCP connections cannot route through intermediate hops without an active BGP session on every transit router

C.Because iBGP packets have an IP TTL fixed to 1 and cannot traverse more than one physical hop

D.Because OSPF cannot redistribute routes learned from BGP unless every OSPF router has an iBGP session

Explanation: Because iBGP speakers do not modify the AS-Path attribute when advertising routes internally, the normal AS-Path loop detection mechanism cannot prevent loops within an AS. To avoid loops, BGP enforces the split-horizon rule: a route learned from an iBGP peer must never be re-advertised to another iBGP peer. Consequently, all routers in the AS must peer directly with each other (full mesh) or utilize Route Reflectors (RFC 4456) with CLUSTER_LIST and ORIGINATOR_ID attributes.

9In an IEEE 802.1Q tagged Ethernet frame, how many bytes does the VLAN tag header add to the standard Ethernet frame, and how many bits are allocated specifically for the VLAN Identifier (VID)?

A.4 bytes added; 12 bits for the VID, allowing up to 4,096 VLAN IDs (0 to 4095)

B.2 bytes added; 16 bits for the VID, allowing up to 65,536 VLAN IDs

C.8 bytes added; 24 bits for the VID, allowing up to 16 million VLAN IDs

D.4 bytes added; 8 bits for the VID, allowing up to 256 VLAN IDs

Explanation: The IEEE 802.1Q tag inserts a 4-byte (32-bit) field between the Source MAC address and the EtherType/Length fields. It consists of a 16-bit Tag Protocol Identifier (TPID = 0x8100) and a 16-bit Tag Control Information (TCI) field. The TCI contains 3 bits of Priority Code Point (PCP/802.1p), 1 bit Drop Eligible Indicator (DEI), and 12 bits for the VLAN ID (VID), supporting values 0 to 4095 (with 0 and 4095 reserved).

10What security risk arises when an IEEE 802.1Q trunk port carries the native VLAN untagged and an attacker on an access port sends double-tagged 802.1Q frames?

A.VLAN hopping; the first switch strips the outer native VLAN tag and forwards the inner tagged frame to a target VLAN on a subsequent switch without router authorization

B.ARP spoofing; the switch overwrites its MAC address table and forwards all unicast traffic to the attacker

C.BPDU denial of service; the second switch interprets the inner tag as an STP topology change notification

D.DHCP exhaustion; the inner tag bypasses DHCP snooping filters on the target VLAN

Explanation: Double-tagging VLAN hopping occurs when an attacker's access port is on the native VLAN of the trunk. The attacker crafts a frame with two tags: an outer tag matching the trunk's native VLAN and an inner tag of the victim VLAN. The first switch removes the outer tag because traffic on the native VLAN is sent untagged across the trunk. The next switch reads the inner tag and delivers the frame to the victim VLAN, circumventing Layer 3 firewall/router inspection.

About the BUT Réseaux et Télécommunications Exam

The Bachelor Universitaire de Technologie (BUT) Réseaux et Télécommunications (R&T) is France's premier three-year undergraduate university diploma for network architecture, telecommunications infrastructure, cybersecurity, and cloud automation (grade de licence, 180 ECTS, Level 6). Governed by national decree (Arrêté du 15 avril 2022 Annexe 22), the curriculum trains engineers and high-level technicians to design, deploy, secure, and automate complex communications systems. Pitched at Bac+3 depth to distinguish it from two-year BTS CIEL technician qualifications, it covers advanced operator networks (MPLS, optical transmission budgets, 5G cores), DevOps network automation (Python, Ansible, RESTCONF), and defense-in-depth cybersecurity. OpenExamPrep provides an English-language MCQ study adaptation of the national French competency framework.

Exam sponsor: Ministère de l'Enseignement Supérieur et de la Recherche / Universités / IUT. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Under the Arrêté du 15 avril 2022 (Annexe 22), the BUT Réseaux et Télécommunications is structured across 6 semesters (180 ECTS) conferring the national grade de licence (Level 6). Delivered by university Instituts Universitaires de Technologie (IUT), students are evaluated through continuous assessment (contrôle continu intégral CCI), multidisciplinary SAÉ projects, 22 to 26 weeks of industrial internships or work-study alternance, and professional portfolio defenses. A common core covering approximately 80% of the programme focuses on network administration, enterprise connectivity, and network tool development, complemented in years 2 and 3 by one of five specialized parcours. Each teaching unit (UE) is validated at 10/20, with compensation permitted within defined coherent UE groupings when the grouping average reaches 10/20 and every constituent UE is at least 8/20.

Time Limit

Three academic years (6 semesters, 180 ECTS)

Passing Score

10/20 to validate each competency UE; compensation within defined groupings requires an average of 10/20 with no UE below 8/20

Exam / Certification Fees

No separate national examination fee; university registration charges and the CVEC are published annually, with exemptions applying in defined cases

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

25 of 100 questions

Advanced IP Networking, Routing & Services

IPv4 and IPv6 addressing and subnetting, multi-area OSPF, BGP routing, VLAN trunking (802.1Q), spanning tree, enterprise DNS/DHCP architectures, and QoS traffic engineering.

20 of 100 questions

Telecom Transmissions, Optical & Mobile Networks

Optical fiber transmission, attenuation and dispersion budget calculations, radio wave propagation, antenna gain, 4G/5G mobile cellular architectures, and VoIP/SIP telephony.

20 of 100 questions

Network Programming, Automation & Cloud DevOps

Python network scripting, Netmiko and Paramiko automation, RESTCONF/NETCONF, structured data (JSON, YAML), Linux systems administration, Docker container networks, and virtualization.

20 of 100 questions

Infrastructure Cybersecurity & Network Defense

Stateful and next-generation firewalls, cryptographic fundamentals, IPsec and TLS VPNs, 802.1X/RADIUS authentication, intrusion detection (IDS/IPS), and ANSSI hygiene rules.

15 of 100 questions

Operator Networks, IoT & Telecom Project Management

MPLS core architectures, Carrier Ethernet, IoT connectivity protocols (LoRaWAN, MQTT), ARCEP telecom regulatory frameworks, SLA metrics, and network project management.

Preparing for the BUT Réseaux et Télécommunications Exam

What You Need to Know

Passing score: 10/20 to validate each competency UE; compensation within defined groupings requires an average of 10/20 with no UE below 8/20
Assessment: Under the Arrêté du 15 avril 2022 (Annexe 22), the BUT Réseaux et Télécommunications is structured across 6 semesters (180 ECTS) conferring the national grade de licence (Level 6). Delivered by university Instituts Universitaires de Technologie (IUT), students are evaluated through continuous assessment (contrôle continu intégral CCI), multidisciplinary SAÉ projects, 22 to 26 weeks of industrial internships or work-study alternance, and professional portfolio defenses. A common core covering approximately 80% of the programme focuses on network administration, enterprise connectivity, and network tool development, complemented in years 2 and 3 by one of five specialized parcours. Each teaching unit (UE) is validated at 10/20, with compensation permitted within defined coherent UE groupings when the grouping average reaches 10/20 and every constituent UE is at least 8/20.
Time limit: Three academic years (6 semesters, 180 ECTS)
Exam / certification fees: No separate national examination fee; university registration charges and the CVEC are published annually, with exemptions applying in defined cases Official sources

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BUT Réseaux et Télécommunications: Suggested Study Strategy

1Practice exact quantitative calculations: optical power budgets (attenuation in dB, connector/splice loss, receiver sensitivity), radio link budgets (free-space path loss, EIRP, antenna gain), and IPv4/IPv6 VLSM subnetting.

2Master multi-area OSPF concepts (LSA types 1, 2, 3, ABR/ASBR roles) and BGP path selection attributes (Weight, Local Preference, AS-Path, MED).

3Understand optical transmission physics: single-mode vs multi-mode fiber, chromatic and modal dispersion, WDM/DWDM wavelength multiplexing, and OTDR trace interpretation.

4Review network automation workflows in Python using Netmiko/Paramiko, structured data representations (JSON, YAML), and RESTCONF HTTP verbs.

5Memorize cybersecurity defenses: IPsec phases (IKEv1/IKEv2 main/aggressive modes, ESP vs AH), 802.1X EAP mechanisms, TLS handshake flow, and ANSSI network hygiene rules.

Frequently Asked Questions

What is the BUT Réseaux et Télécommunications (R&T)?

The Bachelor Universitaire de Technologie (BUT) R&T is a three-year French national undergraduate degree (grade de licence, 180 ECTS, Level 6 RNCP) delivered by university Institutes of Technology (IUT). It prepares professionals to engineer, administer, and secure computer networks, telecommunications infrastructures, and cloud environments.

How does the BUT R&T differ from the BTS CIEL?

While the BTS CIEL is a two-year Level 5 technician diploma (120 ECTS) focusing on electronics and basic systems integration, the BUT R&T is a three-year Level 6 bachelor qualification (180 ECTS). The BUT R&T emphasizes advanced telecommunications (optical link budgets, 5G architectures, radio propagation), cloud infrastructure automation (Python, Ansible, containerization), operator routing (BGP, MPLS), and strategic project leadership.

How are students evaluated in the BUT R&T?

Assessment is continuous across all six semesters (contrôle continu intégral CCI). It includes written examinations, technical laboratory evaluations, Situations d'Apprentissage et d'Évaluation (SAÉ - simulated real-world telecom deployments, network design audits, and security implementations), 22 to 26 weeks of industrial internships or alternance, and professional portfolio defenses.

What specializations (parcours) exist in the BUT R&T?

From the second year, students choose from five national parcours: 1. Cybersécurité; 2. Développement système et cloud; 3. Internet des objets et mobilité; 4. Pilotage de projets de réseaux; and 5. Réseaux opérateurs et multimédia.

What language does this BUT R&T practice bank use?

While official French university instruction is delivered in French, OpenExamPrep provides an English-language MCQ study adaptation. It tests the quantitative calculations, routing protocols, transmission mathematics, and security architectures required by the French curriculum, but does not simulate physical lab cabling or oral portfolio defenses.

What three core competencies form the 80% common foundation of BUT R&T?

Annexe 22 of the Arrêté du 15 avril 2022 defines three core competencies representing ~80% of the programme: 1. Administrer les réseaux et l'Internet; 2. Connecter les entreprises et les usagers; and 3. Créer des outils et applications pour les réseaux et télécommunications.