Find the Arbitrum batch containing a child block
A parent-chain batch can contain many child blocks. A support ticket containing a child block number needs a mapping step before an operator can look up the corresponding parent posting.
Ask the child node for the batch number
Set CHILD_BLOCK to the decimal child height and CHILD_RPC to the corresponding Nitro RPC endpoint. Foundry cast invokes the RPC-only NodeInterface. Preserve the returned number together with the child chain identity.
cast call 0x00000000000000000000000000000000000000C8 \
"findBatchContainingBlock(uint64)(uint64)" "$CHILD_BLOCK" --rpc-url "$CHILD_RPC"
If block 42000 maps to batch 91, search the configured parent SequencerInbox records for batch 91. The number 91 is the batch identifier, not the parent block height or a child transaction index.
Handle a block ahead of publication
A recent child block may be visible through the sequencer before the node can associate it with a posted batch. A failed lookup can also reflect missing historical indexes or the wrong backend. Check node progress and parent publication before declaring the block orphaned. github.com Arbitrum documentation