Challenge library

240 hands-on labs · 10 free. Filter by protocol, difficulty, or time.

How labs work

240 challenges

CHALLENGETOPICDIFFICULTYEST. TIMEACCESS

001The unreachable branchstatic · troubleshootingRoutingEasy8 minFree

002A neighbor gone quietospf · multi-serviceOSPFMedium25 minFree

003The silent peeringbgp · multi-serviceBGPMedium25 minFree

004Green links. Broken checkout.static · multi-serviceSecurityHard25 minFree

005The route to nowherestatic · multi-serviceNetwork operationsMedium25 minFree

006Going in circlesstatic · multi-serviceNetwork operationsHard25 minFree

007The missing way homestatic · multi-serviceRoutingHard25 minFree

008A little too quietospf · multi-serviceOSPFMedium20 minFree

009Everyone is a neighborospf · multi-serviceOSPFEasy15 minFree

010A prefix without a voicebgp · multi-serviceBGPMedium20 minFree

011Warehouse scanners offlinestatic · multi-serviceRoutingEasy15 min

012The forgotten subnetstatic · multi-serviceRoutingHard30 min

013After the cleanup windowstatic · multi-serviceRoutingEasy15 min

014A branch left behindstatic · multi-serviceRoutingHard30 min

015The overnight discardospf · multi-serviceOSPFHard25 min

016A route with no exitstatic · multi-serviceNetwork operationsMedium25 min

017The disappearing packetsospf · multi-serviceOSPFHard25 min

018An overzealous aggregatestatic · multi-serviceNetwork operationsMedium25 min

019A transit detourstatic · multi-serviceRoutingMedium25 min

020The wrong turnstatic · multi-serviceNetwork operationsHard25 min

021A circular dependencystatic · multi-serviceRoutingMedium25 min

022Two routers, no progressstatic · multi-serviceNetwork operationsHard25 min

023Requests without repliesstatic · multi-serviceRoutingHard25 min

024Half a connectionstatic · multi-serviceRoutingHard25 min

025Service-side blind spotstatic · multi-serviceRoutingHard25 min

026The one-way changestatic · multi-serviceRoutingHard25 min

027The backbone boundaryospf · multi-serviceOSPFMedium25 min

028The isolated service leafospf · multi-serviceOSPFMedium25 min

029Lost after an area changeospf · multi-serviceOSPFMedium25 min

030Same subnet, different worldsospf · multi-serviceOSPFMedium25 min

031Hardening gone sidewaysospf · multi-serviceOSPFExpert35 min

032An empty neighbor tableospf · multi-serviceOSPFMedium20 min

033The quiet transitospf · multi-serviceOSPFExpert35 min

034No hello from the coreospf · multi-serviceOSPFMedium20 min

035Connected, never advertisedospf · multi-serviceOSPFEasy15 min

036The missing service LSAospf · multi-serviceOSPFEasy15 min

037Neighbors are not enoughospf · multi-serviceOSPFEasy15 min

038The unannounced networkospf · multi-serviceOSPFEasy15 min

039The onboarding typobgp · multi-serviceBGPMedium25 min

040Who is on the other end?bgp · multi-serviceBGPMedium25 min

041Peering after the migrationbgp · multi-serviceBGPMedium25 min

042The mismatched neighborbgp · multi-serviceBGPMedium25 min

043The service nobody learnedbgp · multi-serviceBGPHard25 min

044A healthy but empty peerbgp · multi-serviceBGPExpert35 min

045Origination after the movebgp · multi-serviceBGPMedium20 min

046A connected prefix stays localbgp · multi-serviceBGPHard25 min

047The payment gateway lockoutstatic · multi-serviceSecurityMedium25 min

048The overly broad denystatic · multi-serviceSecurityHard25 min

049A secure but unavailable servicestatic · multi-serviceSecurityMedium20 min

050Restore access, preserve isolationstatic · multi-serviceSecurityExpert35 min

051One host disappears inside a healthy subnetstatic · production troubleshootingRoutingHard25 min

052Half a subnet takes a circular detourstatic · production troubleshootingRoutingHard25 min

053The new application host is outside the routestatic · production troubleshootingRoutingHard25 min

054Requests arrive but the client never hears backstatic · production troubleshootingRoutingHard25 min

055A second client subnet was left outstatic · production troubleshootingRoutingHard25 min

056OSPF is healthy but a host still vanishesospf · production troubleshootingOSPFHard25 min

057A valid BGP prefix with a hidden forwarding trapbgp · production troubleshootingBGPHard25 min

058The application is sent to the telemetry edgestatic · production troubleshootingRoutingHard25 min

059The second application loops at the corestatic · production troubleshootingRoutingHard25 min

060One repair is not enough after the route cleanupstatic · production troubleshootingRoutingHard30 min

061Only one client address can receive repliesstatic · production troubleshootingRoutingHard25 min

062A summary route hides a missing service prefixstatic · production troubleshootingRoutingHard25 min

063One connected subnet never entered OSPFospf · production troubleshootingOSPFHard25 min

064The telemetry hardening change stopped routingospf · production troubleshootingOSPFHard25 min

065Only one side of the branch area changedospf · production troubleshootingOSPFHard25 min

066The advertised network misses the actual loopbackospf · production troubleshootingOSPFHard25 min

067Neighbors recover but the application does notospf · production troubleshootingOSPFExpert35 min

068A telemetry peer expects the wrong ASbgp · production troubleshootingBGPHard25 min

069The second service was never originatedbgp · production troubleshootingBGPHard25 min

070Peering and forwarding both need repairbgp · production troubleshootingBGPExpert35 min

071BGP origination has the wrong prefix lengthbgp · production troubleshootingBGPHard25 min

072A telemetry prefix was mistyped at originationbgp · production troubleshootingBGPHard25 min

073A permit exists but an earlier rule winsstatic · production troubleshootingSecurityHard25 min

074The policy is correct on the wrong interfacestatic · production troubleshootingSecurityHard25 min

075The right port with the wrong transportstatic · production troubleshootingSecurityHard25 min

076The lower half of the client subnet worksstatic · production troubleshootingSecurityHard25 min

077The lower half of the service subnet worksstatic · production troubleshootingSecurityHard25 min

078The reverse path has its own security boundarystatic · production troubleshootingSecurityHard25 min

079One DNS transport path is missingstatic · production troubleshootingSecurityHard25 min

080Restore two services without opening the boundarystatic · production troubleshootingSecurityExpert35 min

081Campus: The primary service is unreachablecampus · staticRoutingEasy15 min

082Campus: Traffic returns to the client edgecampus · staticRoutingMedium25 min

083Campus: One service address drops outcampus · staticNetwork operationsMedium25 min

084Campus: Only the upper half respondscampus · staticNetwork operationsHard25 min

085Campus: The second client subnet gets no replycampus · staticRoutingHard25 min

086Campus: Both services fail after route cleanupcampus · staticRoutingHard30 min

087Campus: One subnet is absent from the routing domaincampus · ospfOSPFEasy15 min

088Campus: The service edge loses its neighborcampus · ospfOSPFMedium25 min

089Campus: Hardening interrupts service reachabilitycampus · ospfOSPFMedium20 min

090Campus: A healthy control plane hides a dropped hostcampus · ospfOSPFHard25 min

091Campus: Neighbor recovery is only the first repaircampus · ospfOSPFExpert35 min

092Campus: The service edge stops exchanging BGP routescampus · bgpBGPMedium25 min

093Campus: A new service prefix never reaches clientscampus · bgpBGPMedium20 min

094Campus: The advertised prefix does not match the servicecampus · bgpBGPHard25 min

095Campus: Export recovery leaves a return-path failurecampus · bgpBGPExpert35 min

096Campus: The permit rule is present but traffic failscampus · staticSecurityHard25 min

097Campus: New client addresses cannot use the servicecampus · staticSecurityMedium25 min

098Campus: The new service host fails its network checkcampus · staticSecurityHard25 min

099Campus: The port is open for the wrong trafficcampus · staticSecurityMedium20 min

100Campus: Restore both services without opening the boundarycampus · staticSecurityExpert35 min

101Branch WAN: The primary service is unreachablebranch wan · staticRoutingEasy15 min

102Branch WAN: Traffic returns to the client edgebranch wan · staticRoutingMedium25 min

103Branch WAN: One service address drops outbranch wan · staticNetwork operationsMedium25 min

104Branch WAN: Only the upper half respondsbranch wan · staticNetwork operationsHard25 min

105Branch WAN: The second client subnet gets no replybranch wan · staticRoutingHard25 min

106Branch WAN: Both services fail after route cleanupbranch wan · staticRoutingHard30 min

107Branch WAN: One subnet is absent from the routing domainbranch wan · ospfOSPFEasy15 min

108Branch WAN: The service edge loses its neighborbranch wan · ospfOSPFMedium25 min

109Branch WAN: Hardening interrupts service reachabilitybranch wan · ospfOSPFMedium20 min

110Branch WAN: A healthy control plane hides a dropped hostbranch wan · ospfOSPFHard25 min

111Branch WAN: Neighbor recovery is only the first repairbranch wan · ospfOSPFExpert35 min

112Branch WAN: The service edge stops exchanging BGP routesbranch wan · bgpBGPMedium25 min

113Branch WAN: A new service prefix never reaches clientsbranch wan · bgpBGPMedium20 min

114Branch WAN: The advertised prefix does not match the servicebranch wan · bgpBGPHard25 min

115Branch WAN: Export recovery leaves a return-path failurebranch wan · bgpBGPExpert35 min

116Branch WAN: The permit rule is present but traffic failsbranch wan · staticSecurityHard25 min

117Branch WAN: New client addresses cannot use the servicebranch wan · staticSecurityMedium25 min

118Branch WAN: The new service host fails its network checkbranch wan · staticSecurityHard25 min

119Branch WAN: The port is open for the wrong trafficbranch wan · staticSecurityMedium20 min

120Branch WAN: Restore both services without opening the boundarybranch wan · staticSecurityExpert35 min

121Data center: The primary service is unreachabledata center · staticRoutingEasy15 min

122Data center: Traffic returns to the client edgedata center · staticRoutingMedium25 min

123Data center: One service address drops outdata center · staticNetwork operationsMedium25 min

124Data center: Only the upper half respondsdata center · staticNetwork operationsHard25 min

125Data center: The second client subnet gets no replydata center · staticRoutingHard25 min

126Data center: Both services fail after route cleanupdata center · staticRoutingHard30 min

127Data center: One subnet is absent from the routing domaindata center · ospfOSPFEasy15 min

128Data center: The service edge loses its neighbordata center · ospfOSPFMedium25 min

129Data center: Hardening interrupts service reachabilitydata center · ospfOSPFMedium20 min

130Data center: A healthy control plane hides a dropped hostdata center · ospfOSPFHard25 min

131Data center: Neighbor recovery is only the first repairdata center · ospfOSPFExpert35 min

132Data center: The service edge stops exchanging BGP routesdata center · bgpBGPMedium25 min

133Data center: A new service prefix never reaches clientsdata center · bgpBGPMedium20 min

134Data center: The advertised prefix does not match the servicedata center · bgpBGPHard25 min

135Data center: Export recovery leaves a return-path failuredata center · bgpBGPExpert35 min

136Data center: The permit rule is present but traffic failsdata center · staticSecurityHard25 min

137Data center: New client addresses cannot use the servicedata center · staticSecurityMedium25 min

138Data center: The new service host fails its network checkdata center · staticSecurityHard25 min

139Data center: The port is open for the wrong trafficdata center · staticSecurityMedium20 min

140Data center: Restore both services without opening the boundarydata center · staticSecurityExpert35 min

141Regional operations: The primary service is unreachableregional operations · staticRoutingEasy15 min

142Regional operations: Traffic returns to the client edgeregional operations · staticRoutingMedium25 min

143Regional operations: One service address drops outregional operations · staticNetwork operationsMedium25 min

144Regional operations: Only the upper half respondsregional operations · staticNetwork operationsHard25 min

145Regional operations: The second client subnet gets no replyregional operations · staticRoutingHard25 min

146Regional operations: Both services fail after route cleanupregional operations · staticRoutingHard30 min

147Regional operations: One subnet is absent from the routing domainregional operations · ospfOSPFEasy15 min

148Regional operations: The service edge loses its neighborregional operations · ospfOSPFMedium25 min

149Regional operations: Hardening interrupts service reachabilityregional operations · ospfOSPFMedium20 min

150Regional operations: A healthy control plane hides a dropped hostregional operations · ospfOSPFHard25 min

151Regional operations: Neighbor recovery is only the first repairregional operations · ospfOSPFExpert35 min

152Regional operations: The service edge stops exchanging BGP routesregional operations · bgpBGPMedium25 min

153Regional operations: A new service prefix never reaches clientsregional operations · bgpBGPMedium20 min

154Regional operations: The advertised prefix does not match the serviceregional operations · bgpBGPHard25 min

155Regional operations: Export recovery leaves a return-path failureregional operations · bgpBGPExpert35 min

156Regional operations: The permit rule is present but traffic failsregional operations · staticSecurityHard25 min

157Regional operations: New client addresses cannot use the serviceregional operations · staticSecurityMedium25 min

158Regional operations: The new service host fails its network checkregional operations · staticSecurityHard25 min

159Regional operations: The port is open for the wrong trafficregional operations · staticSecurityMedium20 min

160Regional operations: Restore both services without opening the boundaryregional operations · staticSecurityExpert35 min

161Service edge: The primary service is unreachableservice edge · staticRoutingEasy15 min

162Service edge: Traffic returns to the client edgeservice edge · staticRoutingMedium25 min

163Service edge: One service address drops outservice edge · staticNetwork operationsMedium25 min

164Service edge: Only the upper half respondsservice edge · staticNetwork operationsHard25 min

165Service edge: The second client subnet gets no replyservice edge · staticRoutingHard25 min

166Service edge: Both services fail after route cleanupservice edge · staticRoutingHard30 min

167Service edge: One subnet is absent from the routing domainservice edge · ospfOSPFEasy15 min

168Service edge: The service edge loses its neighborservice edge · ospfOSPFMedium25 min

169Service edge: Hardening interrupts service reachabilityservice edge · ospfOSPFMedium20 min

170Service edge: A healthy control plane hides a dropped hostservice edge · ospfOSPFHard25 min

171Service edge: Neighbor recovery is only the first repairservice edge · ospfOSPFExpert35 min

172Service edge: The service edge stops exchanging BGP routesservice edge · bgpBGPMedium25 min

173Service edge: A new service prefix never reaches clientsservice edge · bgpBGPMedium20 min

174Service edge: The advertised prefix does not match the serviceservice edge · bgpBGPHard25 min

175Service edge: Export recovery leaves a return-path failureservice edge · bgpBGPExpert35 min

176Service edge: The permit rule is present but traffic failsservice edge · staticSecurityHard25 min

177Service edge: New client addresses cannot use the serviceservice edge · staticSecurityMedium25 min

178Service edge: The new service host fails its network checkservice edge · staticSecurityHard25 min

179Service edge: The port is open for the wrong trafficservice edge · staticSecurityMedium20 min

180Service edge: Restore both services without opening the boundaryservice edge · staticSecurityExpert35 min

181Backup network: The primary service is unreachablebackup network · staticRoutingEasy15 min

182Backup network: Traffic returns to the client edgebackup network · staticRoutingMedium25 min

183Backup network: One service address drops outbackup network · staticNetwork operationsMedium25 min

184Backup network: Only the upper half respondsbackup network · staticNetwork operationsHard25 min

185Backup network: The second client subnet gets no replybackup network · staticRoutingHard25 min

186Backup network: Both services fail after route cleanupbackup network · staticRoutingHard30 min

187Backup network: One subnet is absent from the routing domainbackup network · ospfOSPFEasy15 min

188Backup network: The service edge loses its neighborbackup network · ospfOSPFMedium25 min

189Backup network: Hardening interrupts service reachabilitybackup network · ospfOSPFMedium20 min

190Backup network: A healthy control plane hides a dropped hostbackup network · ospfOSPFHard25 min

191Backup network: Neighbor recovery is only the first repairbackup network · ospfOSPFExpert35 min

192Backup network: The service edge stops exchanging BGP routesbackup network · bgpBGPMedium25 min

193Backup network: A new service prefix never reaches clientsbackup network · bgpBGPMedium20 min

194Backup network: The advertised prefix does not match the servicebackup network · bgpBGPHard25 min

195Backup network: Export recovery leaves a return-path failurebackup network · bgpBGPExpert35 min

196Backup network: The permit rule is present but traffic failsbackup network · staticSecurityHard25 min

197Backup network: New client addresses cannot use the servicebackup network · staticSecurityMedium25 min

198Backup network: The new service host fails its network checkbackup network · staticSecurityHard25 min

199Backup network: The port is open for the wrong trafficbackup network · staticSecurityMedium20 min

200Backup network: Restore both services without opening the boundarybackup network · staticSecurityExpert35 min

201Industrial campus: The primary service is unreachableindustrial campus · staticRoutingEasy15 min

202Industrial campus: Traffic returns to the client edgeindustrial campus · staticRoutingMedium25 min

203Industrial campus: One service address drops outindustrial campus · staticNetwork operationsMedium25 min

204Industrial campus: Only the upper half respondsindustrial campus · staticNetwork operationsHard25 min

205Industrial campus: The second client subnet gets no replyindustrial campus · staticRoutingHard25 min

206Industrial campus: Both services fail after route cleanupindustrial campus · staticRoutingHard30 min

207Industrial campus: One subnet is absent from the routing domainindustrial campus · ospfOSPFEasy15 min

208Industrial campus: The service edge loses its neighborindustrial campus · ospfOSPFMedium25 min

209Industrial campus: Hardening interrupts service reachabilityindustrial campus · ospfOSPFMedium20 min

210Industrial campus: A healthy control plane hides a dropped hostindustrial campus · ospfOSPFHard25 min

211Industrial campus: Neighbor recovery is only the first repairindustrial campus · ospfOSPFExpert35 min

212Industrial campus: The service edge stops exchanging BGP routesindustrial campus · bgpBGPMedium25 min

213Industrial campus: A new service prefix never reaches clientsindustrial campus · bgpBGPMedium20 min

214Industrial campus: The advertised prefix does not match the serviceindustrial campus · bgpBGPHard25 min

215Industrial campus: Export recovery leaves a return-path failureindustrial campus · bgpBGPExpert35 min

216Industrial campus: The permit rule is present but traffic failsindustrial campus · staticSecurityHard25 min

217Industrial campus: New client addresses cannot use the serviceindustrial campus · staticSecurityMedium25 min

218Industrial campus: The new service host fails its network checkindustrial campus · staticSecurityHard25 min

219Industrial campus: The port is open for the wrong trafficindustrial campus · staticSecurityMedium20 min

220Industrial campus: Restore both services without opening the boundaryindustrial campus · staticSecurityExpert35 min

221Remote access: The primary service is unreachableremote access · staticRoutingEasy15 min

222Remote access: Traffic returns to the client edgeremote access · staticRoutingMedium25 min

223Remote access: One service address drops outremote access · staticNetwork operationsMedium25 min

224Remote access: Only the upper half respondsremote access · staticNetwork operationsHard25 min

225Remote access: The second client subnet gets no replyremote access · staticRoutingHard25 min

226Remote access: Both services fail after route cleanupremote access · staticRoutingHard30 min

227Remote access: One subnet is absent from the routing domainremote access · ospfOSPFEasy15 min

228Remote access: The service edge loses its neighborremote access · ospfOSPFMedium25 min

229Remote access: Hardening interrupts service reachabilityremote access · ospfOSPFMedium20 min

230Remote access: A healthy control plane hides a dropped hostremote access · ospfOSPFHard25 min

231Remote access: Neighbor recovery is only the first repairremote access · ospfOSPFExpert35 min

232Remote access: The service edge stops exchanging BGP routesremote access · bgpBGPMedium25 min

233Remote access: A new service prefix never reaches clientsremote access · bgpBGPMedium20 min

234Remote access: The advertised prefix does not match the serviceremote access · bgpBGPHard25 min

235Remote access: Export recovery leaves a return-path failureremote access · bgpBGPExpert35 min

236Remote access: The permit rule is present but traffic failsremote access · staticSecurityHard25 min

237Remote access: New client addresses cannot use the serviceremote access · staticSecurityMedium25 min

238Remote access: The new service host fails its network checkremote access · staticSecurityHard25 min

239Remote access: The port is open for the wrong trafficremote access · staticSecurityMedium20 min

240Remote access: Restore both services without opening the boundaryremote access · staticSecurityExpert35 min

Every incident includes a simulated network and automated repair checks.How the labs work